Employee Benefits - Assumptions (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2016	Dec. 31, 2024	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net periodic cost
Weighted-average healthcare cost rate				7.00%
Effects created by one percentage point change in assumed healthcare cost trend
Effect of 1% point increase on postretirement obligation				$ 4
Effect of 1% point decrease on postretirement obligation				$ (3)
Retirement Plans [Member]
Benefit obligation
Discount rate				4.47%	4.15%	5.00%
Net periodic cost
Discount rate				4.15%	5.00%	4.10%
Return on assets				6.25%	7.125%	7.25%
Postretirement Plans [Member]
Benefit obligation
Discount rate				3.90%	3.60%	4.20%
Net periodic cost
Weighted-average healthcare cost rate				7.00%	7.00%	7.00%
Discount rate				3.60%	4.125%	3.45%
United Kingdom Retirement Plan [Member]
Net periodic cost
Discount rate				3.80%	4.50%	4.80%
Compensation increase factor						5.75%
United States Pension Plan of US Entity [Member]
Net periodic cost
Discount rate				4.15%
Subsequent Event [Member] | Retirement Plans [Member]
Net periodic cost
Return on assets	6.25%
Subsequent Event [Member] | United Kingdom Retirement Plan [Member]
Net periodic cost
Discount rate	3.84%
Subsequent Event [Member] | United States Pension Plan of US Entity [Member]
Net periodic cost
Discount rate	4.47%
Scenario, Forecast [Member]
Net periodic cost
Weighted-average healthcare cost rate		5.00%
Change in Accounting Method Accounted for as Change in Estimate [Member] | Scenario, Forecast [Member]
Net periodic cost
Decrease in pension and postretirement medical costs			$ 13