Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Refund of AMT credit carryforwards			$ 572	$ 573
Deferred tax liabilities			$ 117
State
Income Tax Disclosure [Line Items]
Reduction in deferred tax liability	$ 490
Reduction of deferred tax assets	$ 25
AMT credit carryforwards
Income Tax Disclosure [Line Items]
Refund of AMT credit carryforwards		$ 572
Income tax interest income		$ 19