Retirement and Other Postretirement Benefit Plans - Schedule of Actual Allocations for the Pension Assets and Target Allocations by Asset Class (Details)	Dec. 31, 2019	Dec. 31, 2018
Change in plan assets:
Percentage of Plan Assets	100.00%	100.00%
Target Allocations	100.00%	100.00%
Diversified Growth Funds
Change in plan assets:
Percentage of Plan Assets	25.90%	24.10%
Target Allocations	22.30%	28.00%
Index Linked Gilts
Change in plan assets:
Percentage of Plan Assets	34.30%	30.90%
Target Allocations	33.40%	12.60%
Fixed Interest Gilts
Change in plan assets:
Percentage of Plan Assets	9.30%
Target Allocations	9.10%
Liability Driven Investments
Change in plan assets:
Percentage of Plan Assets	13.80%	17.20%
Target Allocations	16.50%	23.20%
All Other Regions Equity Fund
Change in plan assets:
Percentage of Plan Assets	9.20%	14.40%
Target Allocations	10.80%	19.70%
U.K. Equity Fund
Change in plan assets:
Percentage of Plan Assets	4.00%	9.70%
Target Allocations	4.70%	13.20%
Diversified Investment, Funds
Change in plan assets:
Percentage of Plan Assets	1.10%	1.10%
Target Allocations	1.10%	1.10%
Insurance contracts
Change in plan assets:
Percentage of Plan Assets	2.00%	2.30%
Target Allocations	2.10%	2.20%
Cash and Cash Equivalents
Change in plan assets:
Percentage of Plan Assets	0.40%	0.30%