Income Taxes Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Provision (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Current income tax provision (benefit)									$ 2,014	$ (271)	$ 1,879
Deferred income tax provision									4,006	5,524	5,062
Provision for federal income taxes	$ 2,545	$ 1,527	$ 1,398	$ 550	$ 1,103	$ 1,070	$ 2,210	$ 870	$ 6,020	$ 5,253	$ 6,941
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory corporate tax rate									35.00%	35.00%	35.00%
Equity investments in affordable housing projects									(1.90%)	(2.60%)	(1.80%)
Other									(0.30%)	0.90%	1.40%
Valuation allowance									0.00%	(0.90%)	(1.80%)
Effective tax rate									32.80%	32.40%	32.80%