Derivative Instruments and Hedging Activities - Commodity Purchases (Details) - Not Designated As Hedging Instruments [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Commodity Purchases [Line Items]
Liability value	$ 37	$ 73
Asset value	0	25
Current Assets [Member]
Commodity Purchases [Line Items]
Asset value	0	20
Current Assets [Member] | Gas Contract
Commodity Purchases [Line Items]
Asset value	0	20
Current Liabilities [Member]
Commodity Purchases [Line Items]
Liability value	29	63
Current Liabilities [Member] | Gas Contract
Commodity Purchases [Line Items]
Liability value	29	62
Noncurrent Assets [Member]
Commodity Purchases [Line Items]
Asset value	0	5
Noncurrent Assets [Member] | Gas Contract
Commodity Purchases [Line Items]
Asset value	0	5
Noncurrent Liabilities [Member]
Commodity Purchases [Line Items]
Liability value	8	10
Noncurrent Liabilities [Member] | Gas Contract
Commodity Purchases [Line Items]
Liability value	$ 5	$ 4