Income Taxes - Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current income tax expense:
State income tax	$ 1	$ 2	$ 0
Canadian federal and provincial income tax	83	48	51
Total current income tax expense	84	50	51
Deferred income tax expense/(benefit):
Federal income tax	46	16	(149)
State income tax	11	23	1
Canadian federal and provincial income tax	105	23	(70)
Total deferred income tax expense/(benefit)	162	62	(218)
Total income tax expense/(benefit)	$ 246	$ 112	$ (167)