Pension and Postretirement Benefits (Weighted Average Assumptions - Projected Benefit Obligation And Net Pension And Postemployment Benefit Cost) (Details)

3 Months Ended

9 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Sep. 30, 2019

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Defined Benefit Plan Disclosure [Line Items]

Composite rate of compensation increase for determining benefit obligation

3.00%

3.00%

3.00%

Pension Benefit [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate for determining projected benefit obligation at December 31

3.40%

3.40%

4.50%

3.80%

Weighted-average interest crediting rate for cash balance

3.30%

3.30%

3.70%

3.50%

Long-term rate of return on plan assets

7.00%

7.00%

7.75%

Composite rate of compensation increase for determining benefit obligation

3.00%

3.00%

3.00%

3.00%

Composite rate of compensation increase for determining net cost (benefit)

3.00%

3.00%

3.00%

Pension Benefit [Member] | Service Cost [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate in effect for determining net cost

3.50%

3.90%

4.30%

4.60%

4.10%

^[1],[2]

4.20%

^[1],[2]

4.60%

^[1],[2]

Pension Benefit [Member] | Interest Cost [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate in effect for determining net cost

3.00%

3.20%

3.70%

4.20%

3.50%

^[1],[2]

3.80%

^[1],[2]

3.60%

^[1],[2]

Postretirement Benefit [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate for determining projected benefit obligation at December 31

3.20%

3.20%

4.40%

3.70%

Weighted-average interest crediting rate for cash balance

0.00%

0.00%

0.00%

0.00%

Long-term rate of return on plan assets

5.75%

5.75%

5.75%

Composite rate of compensation increase for determining benefit obligation

3.00%

3.00%

3.00%

3.00%

Composite rate of compensation increase for determining net cost (benefit)

3.00%

3.00%

3.00%

Postretirement Benefit [Member] | Service Cost [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate in effect for determining net cost

3.40%

4.70%

4.40%

^[1],[2]

4.30%

^[1],[2]

4.60%

^[1],[2]

Postretirement Benefit [Member] | Interest Cost [Member]

Defined Benefit Plan Disclosure [Line Items]

Discount rate in effect for determining net cost

2.70%

4.00%

3.70%

^[1],[2]

3.60%

^[1],[2]

3.40%

^[1],[2]

[1]	Weighted-average discount rate for pension benefits in effect from January 1, 2019 through March 31, 2019 was 4.60% for service cost and 4.20% for interest cost, from April 1, 2019 through June 30, 2019 was 4.30% for service cost and 3.70% for interest cost, from July 1, 2019
[2]	Weighted-average discount rate for postretirement benefits in effect from January 1, 2019 through October 1, 2019 was 4.70% for service cost and 4.00% for interest cost, and, from October 2, 2019 through December 31, 2019 was 3.40% for service cost and 2.70% for interest cost.