Pension Benefits (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2017	Mar. 31, 2017	[2]	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits						$ 47		$ 7
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 4			$ 4	12		12
Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits		2			0	2		0
UNITED STATES | General and Administrative Expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		2			4	8		12
UNITED STATES | Other pension (income) expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		9			12	29		37
Expected return on plan assets		(10)			(15)	(33)		(45)
Amortization of net loss		1			1	4		4
Amortization of prior service cost		2			2	4		4
Additional loss (gain) recognized due to settlements	[1]	8			(1)	(16)		(1)
Pension data adjustment		$ 0	$ 22		$ 0	$ 22	[2]	$ 0

[1] Losses are a result of settlement transactions in each of our U.S. plans which exceeded the sum of annual service and interest costs for each plan. These losses were recorded in Other pension (income) expense.

[2] Reflects a non-cash, out-of-year charge related to the adjustment of certain historical deferred vested liability balances in the Plan during the first quarter of 2017 recorded in Other pension (income) expense. See Note 5.