Income Taxes Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Rate Reconciliation [Line Items]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		$ 944	$ 793	$ 583
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount		$ 25	$ 12	$ 21
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		0.90%	0.50%	1.20%
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount		$ (88)	$ (89)	$ (80)
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent		(3.30%)	(3.90%)	(4.80%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Restructuring Charges, Amount		$ 0	$ 0	$ (343)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Restructuring Charges, Percent		0.00%	0.00%	(20.60%)
Effective Income Tax Rate Reconciliation, Change in UTBs, Amount		$ (31)	$ (82)	$ 152
Effective Income Tax Rate Reconciliation, Change in UTBs, Percent		(1.10%)	(3.60%)	9.10%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	[1]	(2.60%)	(2.90%)	(3.20%)
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	[1]	$ 69	$ 65	$ 53
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount		$ 0	$ 57	$ (49)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent		0.00%	(2.50%)	3.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		$ (17)	$ (19)	$ (7)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		(0.60%)	(0.80%)	(0.40%)
Income Tax Expense (Benefit)	[2],[3]	$ 764	$ 493	$ 322
Effective Income Tax Rate Reconciliation, Percent		28.30%	21.80%	19.30%

[1] Excludes tax credits of $8 million, $21 million, and $0 for the years ended December 31, 2015, 2014, and 2013, respectively, which were recognized as a reduction to the related investment asset.

[2] Amortization expense related to qualified affordable housing investment costs is recognized in provision for income taxes for each of the periods presented as allowed by an accounting standard adopted in 2014. Accordingly, $49 million of related amortization expense for the year ended December 31, 2013 was reclassified from other noninterest expense to provision for income taxes.

[3] Amortization expense related to qualified affordable housing investment costs is recognized in the provision for income taxes for each of the periods presented as allowed by an accounting standard adopted in 2014. Prior to 2014, these amounts were recognized in other noninterest expense.