Supplemental Cash Flow Disclosures - NPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Cash Flow Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,096	$ 1,290
Restricted cash and cash equivalents	127	140
Total cash and cash equivalents and restricted cash and cash equivalents	1,244	1,445	$ 1,268	$ 883
Interest paid, net of amounts capitalized	2,041	1,855	1,723
Accrued capital expenditures	834	801	888
NPC
Condensed Cash Flow Statements, Captions [Line Items]
Cash and cash equivalents	33	25
Restricted cash and cash equivalents	12	11
Total cash and cash equivalents and restricted cash and cash equivalents	45	36	25	$ 121
Interest paid, net of amounts capitalized	115	115	126
Income taxes (received) paid, net	63	50	113
Accrued capital expenditures	$ 53	$ 32	$ 49