Income Taxes Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Provision (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Current income tax benefit (provision)										$ 114	$ 600	$ (2,014)
Deferred income tax provision										(4,254)	(16,584)	(4,006)
Provision for federal income taxes		$ (828)	$ (1,045)	$ (1,136)	$ (1,131)	$ (11,489)	$ (1,525)	$ (1,587)	$ (1,383)	$ (4,140)	$ (15,984)	$ (6,020)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory corporate tax rate	21.00%									21.00%	35.00%	35.00%
Equity investments in affordable housing projects										(0.60%)	(1.40%)	(1.90%)
Effect of corporate tax rate change										0.00%	53.60%	0.00%
Other										0.20%	(0.60%)	(0.30%)
Effective tax rate										20.60%	86.60%	32.80%