Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Provisional benefit of revaluation of net DTL due to TCJA			$ 1,500
Benefit of revaluation of net DTL due to TCJA			100
Net operating loss and capital loss carryforwards	$ 568	$ 480
Valuation allowance	454	374
Income tax penalties and interest expense	34	49	$ 19
Income tax penalties and interest accrued	121	$ 173
Unrecognized tax benefits that would impact effective tax rate	$ 651