Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Taxes [Line Items]
Effective tax rate	0.00%	0.00%
Valuation allowance related to operating loss	$ 59
Current income tax expense	4	$ 0
Federal
Income Taxes [Line Items]
Operating loss carryforwards subject to a section 382 limitation	2,000
Operating loss carryforwards	4,000
Deferred tax assets, operating loss carryforwards, subject to expiration	3,000
Deferred tax assets, operating loss carryforwards, not subject to expiration	1,000
Indigo Natural Resources, LLC
Income Taxes [Line Items]
Operating loss carryforwards subject to a section 382 limitation	$ 48