Income Taxes (Components of Deferred Tax Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax liabilities:
Right of use lease asset	$ 45	$ 38
Other	3	2
Total deferred tax liabilities	48	40
Deferred tax assets:
Differences between book and tax basis of property	0	295
Accrued compensation	44	38
Accrued pension costs	6	11
Asset retirement obligations	25	20
Net operating loss carryforward	585	1,117
Future lease payments	46	38
Derivative activity	362	9
Capital loss carryover	28	27
Other	31	24
Total deferred tax assets	1,127	1,579
Valuation allowance	(1,079)	(1,539)	$ (87)
Net deferred tax asset	$ 0	$ 0