Retirement Benefits (Fair Value Disclosures) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan, Percentage of Global Investments in Plan Assets	80.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,918.7	$ 1,879.6	$ 1,518.0
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance			1,518.0
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	9,835.7	9,481.7	8,286.6
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance			8,286.6
Fixed Income Funds [Member]
Defined Benefit Plan, Target Allocation Percentage of Assets	15.00%
Fixed Income Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	61.8	54.7
Fixed Income Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,230.7	1,036.1
Equity Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	92.3	88.9
Equity Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,146.6	1,069.9
Equity Securities [Member]
Defined Benefit Plan, Target Allocation Percentage of Assets	85.00%
Equity Securities [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	39.2	39.4
Equity Securities [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	411.4	400.3
Equity Securities - International [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	158.9	167.2
Equity Securities - International [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	2,337.8	2,483.8
Fixed Income Funds, Emerging Markets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	35.5	38.2
Fixed Income Funds, Emerging Markets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	374.7	382.6
Hedge Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	282.7	266.4
Hedge Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	3,277.6	2,902.3
Real Estate [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	39.0	36.7
Real Estate [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	569.0	521.4
Other Assets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	20.1	51.3
Other Assets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	487.9	685.3
Other Contract [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,189.2	1,136.8
Fair Value, Inputs, Level 1 [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	122.6	134.6
Fair Value, Inputs, Level 1 [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,937.3	2,018.4
Fair Value, Inputs, Level 1 [Member] \| Fixed Income Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Fixed Income Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	112.2	170.2
Fair Value, Inputs, Level 1 [Member] \| Equity Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Equity Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Equity Securities [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	17.2	18.3
Fair Value, Inputs, Level 1 [Member] \| Equity Securities [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	183.8	189.2
Fair Value, Inputs, Level 1 [Member] \| Equity Securities - International [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	58.8	61.6
Fair Value, Inputs, Level 1 [Member] \| Equity Securities - International [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	999.7	1,045.8
Fair Value, Inputs, Level 1 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	8.7	0
Fair Value, Inputs, Level 1 [Member] \| Hedge Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Hedge Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 1 [Member] \| Real Estate [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	39.0	36.7
Fair Value, Inputs, Level 1 [Member] \| Real Estate [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	403.1	368.0
Fair Value, Inputs, Level 1 [Member] \| Other Assets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	7.6	18.0
Fair Value, Inputs, Level 1 [Member] \| Other Assets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	229.8	245.2
Fair Value, Inputs, Level 1 [Member] \| Other Contract [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 2 [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,579.6	1,533.9
Fair Value, Inputs, Level 2 [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	5,076.2	4,860.1
Fair Value, Inputs, Level 2 [Member] \| Fixed Income Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	61.8	53.1
Fair Value, Inputs, Level 2 [Member] \| Fixed Income Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,118.5	850.0
Fair Value, Inputs, Level 2 [Member] \| Equity Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 2 [Member] \| Equity Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	75.2	76.4
Fair Value, Inputs, Level 2 [Member] \| Equity Securities [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	22.0	21.1
Fair Value, Inputs, Level 2 [Member] \| Equity Securities [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	227.6	211.1
Fair Value, Inputs, Level 2 [Member] \| Equity Securities - International [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	100.1	105.6
Fair Value, Inputs, Level 2 [Member] \| Equity Securities - International [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,338.1	1,438.0
Fair Value, Inputs, Level 2 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	35.3	38.2
Fair Value, Inputs, Level 2 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	364.2	382.6
Fair Value, Inputs, Level 2 [Member] \| Hedge Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	158.7	145.8
Fair Value, Inputs, Level 2 [Member] \| Hedge Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,694.5	1,461.9
Fair Value, Inputs, Level 2 [Member] \| Real Estate [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 2 [Member] \| Real Estate [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 2 [Member] \| Other Assets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	12.5	33.3
Fair Value, Inputs, Level 2 [Member] \| Other Assets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	258.1	440.1
Fair Value, Inputs, Level 2 [Member] \| Other Contract [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,189.2	1,136.8
Fair Value, Inputs, Level 3 [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	216.5	211.1
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	211.1	182.2
Defined Benefit Plan, Actual Return on Plan Assets Still Held	7.1	23.9
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	(0.1)	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(0.5)	3.9
Defined Benefit Plan, Transfers Between Measurement Levels	(1.1)	1.1
Fair Value, Inputs, Level 3 [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	2,822.2	2,603.2
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	2,603.2	2,274.9
Defined Benefit Plan, Actual Return on Plan Assets Still Held	152.7	284.6
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	(0.8)	0
Defined Benefit Plan, Purchases, Sales, and Settlements	78.5	32.2
Defined Benefit Plan, Transfers Between Measurement Levels	(11.4)	11.5
Fair Value, Inputs, Level 3 [Member] \| Fixed Income Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	1.6
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	1.6	0.4
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(0.1)	(0.3)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	(0.1)	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(0.3)	0.4
Defined Benefit Plan, Transfers Between Measurement Levels	(1.1)	1.1
Fair Value, Inputs, Level 3 [Member] \| Fixed Income Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	15.9
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	15.9	3.7
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(0.4)	(3.0)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	(0.8)	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(3.3)	3.7
Defined Benefit Plan, Transfers Between Measurement Levels	(11.4)	11.5
Fair Value, Inputs, Level 3 [Member] \| Equity Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	92.3	88.9
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	88.9	81.9
Defined Benefit Plan, Actual Return on Plan Assets Still Held	6.0	13.9
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(2.6)	(6.9)
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Equity Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,071.4	993.5
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	993.5	910.5
Defined Benefit Plan, Actual Return on Plan Assets Still Held	108.2	155.7
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(30.3)	(72.7)
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Equity Securities [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Equity Securities [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Equity Securities - International [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Equity Securities - International [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0.2
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	0
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0
Defined Benefit Plan, Purchases, Sales, and Settlements	0.2
Defined Benefit Plan, Transfers Between Measurement Levels	0
Fair Value, Inputs, Level 3 [Member] \| Fixed Income Funds, Emerging Markets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1.8
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	0
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0.1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0
Defined Benefit Plan, Purchases, Sales, and Settlements	1.7
Defined Benefit Plan, Transfers Between Measurement Levels	0
Fair Value, Inputs, Level 3 [Member] \| Hedge Funds [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	124.0	120.6
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	120.6	99.9
Defined Benefit Plan, Actual Return on Plan Assets Still Held	1.2	10.3
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	2.2	10.4
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Hedge Funds [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	1,583.1	1,440.4
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	1,440.4	1,218.1
Defined Benefit Plan, Actual Return on Plan Assets Still Held	44.6	123.4
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	98.1	98.9
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Real Estate [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	0	0
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0	0
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	0	0
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Real Estate [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	165.9	153.4
Defined Benefit Plan, Fair Value of Plan Assets, Beginning Balance	153.4	142.6
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0.2	8.5
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	12.3	2.3
Defined Benefit Plan, Transfers Between Measurement Levels	0	0
Fair Value, Inputs, Level 3 [Member] \| Other Assets [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Other Assets [Member] \| Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	0
Fair Value, Inputs, Level 3 [Member] \| Other Contract [Member] \| Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance	0	$ 0

Retirement Benefits (Fair Value Disclosures) (Details) (USD $)
In Millions, unless otherwise specified

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Defined Benefit Plan, Percentage of Global Investments in Plan Assets

80.00%

Other Postretirement Benefit Plans, Defined Benefit [Member]

Defined Benefit Plan, Fair Value of Plan Assets, Ending Balance

1,918.7

$ 1,879.6

$ 1,518.0