Selected Quarterly Financial Data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net interest income	$ 534	$ 560	$ 582	$ 597	$ 588	$ 604	$ 638	$ 654	$ 2,273	[1]	$ 2,484	[1]	$ 2,470	[1]
Provision for credit losses	(45)	(22)	(21)	(77)	19	62	134	157	(165)		372	[2]	361
Net interest income after provision for credit losses	579	582	603	674	569	542	504	497	2,438		2,112		2,109
Total other revenues	458	393	558	593	282	338	307	477	2,002	[3]	1,404	[3]	1,735	[3]
Operating expenses	903	820	849	819	899	821	837	741	3,391	[3]	3,298	[3],[4]	3,284	[3],[4]
Income (loss) before income tax	134	155	312	448	(48)	59	(26)	233	1,049		218		560
Income tax expense (benefit)	907	61	108	152	(11)	26	(5)	79	1,228		89		230
Net income (loss)	$ (773)	$ 94	$ 204	$ 296	$ (37)	$ 33	$ (21)	$ 154	$ (179)		$ 129		$ 330

[1] Net interest income of each segment represents the difference between actual interest earned on assets and interest paid on liabilities of the segment adjusted for a funding charge or credit. Segments are charged a cost to fund assets (e.g. customer loans) and receive a funding credit for funds provided (e.g. customer deposits) based on equivalent market rates. The objective of these charges/credits is to transfer interest rate risk from the segments to one centralized unit in Balance Sheet Management and more appropriately reflect the profitability of the segments.

[2] The provision for credit losses and charge-offs for residential mortgage loans during 2016 includes $11 million related to the lower of amortized cost or fair value adjustment attributable to credit factors for loans transferred to held for sale. See Note 7, "Loans Held for Sale," for additional information.

[3] Expenses for the segments include fully apportioned corporate overhead expenses.

[4] In 2017, we changed our presentation for certain cost reimbursements that were previously netted as an offset to affiliate expense. We now present these reimbursements gross in affiliate income. As a result, we have reclassified prior year amounts in order to conform to the current year presentation, which increased both RBWM other operating income and RBWM operating expenses $11 million during the year ended December 31, 2016 and also increased both GB&M other operating income and GB&M operating expenses $61 million and $63 million during the years ended December 31, 2016 and 2015, respectively. See Note 21, "Related Party Transactions," in the accompanying consolidated financial statements for additional information.