Income Taxes - Continuing Operations (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Income Tax Disclosure [Abstract]
Provision for income taxes		$ 48	$ 39	$ 35	$ 35	$ 34	$ 58	$ 82	$ 92	$ 157	$ 266	$ 1,228
Income tax expense (benefit) included in common equity related to:
Unrealized gains (losses) on investment securities										128	(68)	127
Unrealized gains (losses) on fair value option liabilities attributable to our own credit spread										(98)	103	(115)
Unrealized gains (losses) on derivatives designated as cash flow hedges										3
Unrealized gains (losses) on derivatives designated as cash flow hedges											12	(5)
Employer accounting for post-retirement plans										(5)	3	1
Cumulative effect adjustment to initially apply new accounting guidance for stranded tax effects resulting from Tax Legislation(1)	[1]												$ 91
Total income taxes										$ 185	$ 407	$ 1,236

[1] Reflects the adoption of new accounting guidance in 2018 which resulted in a cumulative effect adjustment as of January 1, 2018 to reclassify the stranded tax effects resulting from the change in the Federal corporate income tax rate discussed above from accumulated other comprehensive loss to retained earnings