Pension Benefits (Details) - UNITED STATES - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 3	$ 5	$ 14	$ 14
General and Administrative Expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	6	6
Other pension (income) expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	8	9	24	26
Expected return on plan assets	(11)	(10)	(32)	(32)
Amortization of net loss	3	4	12	11
Amortization of prior service cost	$ 1	$ 0	$ 4	$ 3