Income Taxes - Income Tax (Benefit) Expense Attributable to Income from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
Current Income Tax Expense (Benefit)	$ 115	$ 274	$ 283
Deferred:
Total	(5)	(208)	58
Income tax expense (benefit)	110	66	341
Canadian
Current:
Canadian	16	45	47
Deferred:
Canadian	32	(67)	43
United States
Current:
U.S. Federal	(10)	125	122
U.S. state, net of federal income tax benefit	25	26	20
Deferred:
U.S. Federal	(37)	(82)	8
U.S. state, net of federal income tax benefit	(7)	(27)	0
Other Foreign
Current:
Canadian	84	78	94
Deferred:
Canadian	$ 7	$ (32)	$ 7