A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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- Definition

Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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ACCUMULATED OTHER COMPREHENSIVE INCOME - Change in AOCI by component (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Changes in accumulated other comprehensive income
Balance at the beginning of the period	$ 1,969.9	$ 2,084.8	$ 2,112.4	$ 2,476.6	$ 2,600.6	$ 2,009.6	$ 2,112.4	$ 2,009.6
Other comprehensive income (loss) before reclassifications	0.1
Other comprehensive income (loss), net of tax	(7.5)	(107.0)	10.5	33.7	76.5	(1.9)	(103.9)	108.3
Balance at the end of the period	1,254.5	1,969.9	2,084.8	2,424.4	2,476.6	2,600.6	1,254.5	2,424.4
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income
Balance at the beginning of the period	33.5	140.5	125.6	72.1	(4.4)	(2.5)	125.6	(2.5)
Other comprehensive income (loss) before reclassifications							(102.8)
Amounts reclassified from accumulated other comprehensive income							(1.2)
Other comprehensive income (loss), net of tax	(7.5)	(107.0)	10.5	33.7	76.5	(1.9)	(104.0)
Balance at the end of the period	26.0	$ 33.5	140.5	105.8	$ 72.1	$ (4.4)	26.0	105.8
Accumulated Other Comprehensive Income (Loss) \| Accounting Standards Update 2016-01 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							(0.6)
Accumulated Other Comprehensive Income (Loss) \| Accounting Standards Update 2018-02 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							5.0
Foreign Currency
Changes in accumulated other comprehensive income
Balance at the beginning of the period			129.9				129.9
Other comprehensive income (loss) before reclassifications	(5.7)			34.4			(101.6)	109.3
Amounts reclassified from accumulated other comprehensive income							1.0
Other comprehensive income (loss), net of tax							(100.6)
Balance at the end of the period	33.3						33.3
Foreign Currency \| Accounting Standards Update 2018-02 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							4.0
Pension and Other Benefits (recorded in G&A : Other)
Changes in accumulated other comprehensive income
Balance at the beginning of the period			(6.6)				(6.6)
Other comprehensive income (loss) before reclassifications							(1.4)
Other comprehensive income (loss), net of tax							(1.4)
Balance at the end of the period	(7.4)						(7.4)
Pension and Other Benefits (recorded in G&A : Other) \| Accounting Standards Update 2018-02 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							0.6
Unrealized Gains on Marketable Securities (Recorded in Investment income)
Changes in accumulated other comprehensive income
Balance at the beginning of the period			0.6				0.6
Other comprehensive income (loss) before reclassifications				0.2				$ 0.5
Unrealized Gains on Marketable Securities (Recorded in Investment income) \| Accounting Standards Update 2016-01 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							(0.6)
Unrealized Gain from Equity Method Investees' Cash Flow Hedge
Changes in accumulated other comprehensive income
Balance at the beginning of the period			$ 1.7				1.7
Other comprehensive income (loss) before reclassifications				$ (0.1)			0.2
Amounts reclassified from accumulated other comprehensive income							(2.2)
Other comprehensive income (loss), net of tax							(2.0)
Balance at the end of the period	$ 0.1						0.1
Unrealized Gain from Equity Method Investees' Cash Flow Hedge \| Accounting Standards Update 2018-02 [Member]
Changes in accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive income							$ 0.4