Income Taxes Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Period Increase (Decrease)										$ 205
Income Tax Provision (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Current income tax benefit (provision)									$ (3,803)	(2,089)	$ 114
Deferred income tax provision									729	(1,328)	(4,254)
Provision for federal income taxes	$ (1,139)	$ (1,149)	$ (669)	$ (117)	$ (865)	$ (1,036)	$ (889)	$ (627)	$ (3,074)	$ (3,417)	$ (4,140)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory corporate tax rate									21.00%	21.00%	21.00%
Equity investments in affordable housing projects									(0.10%)	(0.20%)	(0.60%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent									0.00%	(1.20%)	0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent									(0.20%)	(0.20%)	0.20%
Effective tax rate									20.70%	19.40%	20.60%