Pension Benefits (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits				$ 13	$ 9
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost		$ 2	$ 5	6	16
UNITED STATES | General and Administrative Expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1	4	5
UNITED STATES | Other pension (income) expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		10	9	30	27
Expected return on plan assets		(11)	(10)	(33)	(31)
Amortization of net loss		0	4	1	11
Amortization of prior service cost		2	1	4	4
Additional loss (gain) recognized due to settlements	[1]	1	0	3	0
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits		$ 0	$ 1	$ 0	$ 1

[1] Loss is a result of settlement transactions which exceeded the sum of annual service and interest costs for the applicable plan. These losses were recorded in Other pension (income) expense.