Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 markets		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011	Jan. 02, 2013
Number of Primary Geographic Markets											3
Minimum Ownership Percentage to Qualify for Equity Method	20.00%										20.00%
Derivative assets	$ 894					$ 500					$ 894		$ 500
Fair value of derivative liability	661					249					661		249
Commitments to fund additional investments in nonmarketable equity securities	5										5
Underlying assets of funds, estimated liquidation period in years											15 years
Federal Home Loan Bank Stock	7					48					7		48
Federal Reserve Bank Stock	85					85					85		85
Net Deferred Income on Originated Loans	267					287					267		287
Allowance for Credit Losses, Threshold for Individual Evaluation, Nonaccrual Loans	2										2
Increase in Allowance due to Enhancements to Methodology										40
Delinquency Status, Period of Unpaid Scheduled Monthly Payment											30 days
Past Due Period Business Loans Placed On Nonaccrual Status											90 days
Past Due Period Residential Mortgage And Home Equity Loans Placed On Nonaccrual Status											90 days
Maximum Past Due Status Junior Lien Home Equity Placed On Nonaccrual Status											90 days
Number of Reporting Units											3
Notional Amount	21,562	[1]				20,538	[1]				21,562	[1]	20,538	[1]
Defined Benefit Plan Market-related Value Plan Assets, Amortization Period											5 years
Defined Benefit Plan Investment Gain Loss Amortization Adjustment, Allowable Percentage											10.00%
Defined Benefit Plan Actuarial Gain Loss Amortization Adjustment, Allowable Percentage											10.00%
Decrease to accrued income and other assets	(4,438)					(3,888)					(4,438)		(3,888)
Decrease to retained earnings	(7,402)					(7,150)					(7,402)		(7,150)		(6,939)	(6,865)
Increase to other noninterest income											142		168		158
Increase to provision for income taxes	70		73	70	64	50		68	64	63	277		245		241
Impact on net income	149		154	151	139	117		147	143	134	593		541		521
Impact on basic earnings per common share	$ 0.83		$ 0.85	$ 0.83	$ 0.76	$ 0.64		$ 0.80	$ 0.77	$ 0.71	$ 3.28		$ 2.92		$ 2.68
Impact on diluted earnings per common share	$ 0.80		$ 0.82	$ 0.80	$ 0.73	$ 0.62		$ 0.78	$ 0.76	$ 0.70	$ 3.16		$ 2.85		$ 2.67
Premises the Corporation Owns [Member] | Minimum
Premises and Equipment, Useful Life											3 years
Premises the Corporation Owns [Member] | Maximum
Premises and Equipment, Useful Life											33 years
Furniture and Fixtures [Member] | Minimum
Premises and Equipment, Useful Life											3 years
Furniture and Fixtures [Member] | Maximum
Premises and Equipment, Useful Life											8 years
Leasehold Improvements [Member] | Maximum
Premises and Equipment, Useful Life											10 years
Software [Member]
Premises and Equipment, Useful Life											5 years
Recurring
Derivative assets	898					503					898		503
Carrying Value
Nonmarketable equity securities	11	[2]				12	[2]				11	[2]	12	[2]
Visa derivative contract
Fair value of derivative liability	1					2					1		2
Restatement Adjustment
Decrease to accrued income and other assets																	3
Increase to other noninterest income													56		52
Increase to provision for income taxes													56		52
Impact on net income													0		0
Impact on basic earnings per common share													$ 0.00		$ 0.00
Impact on diluted earnings per common share													$ 0.00		$ 0.00
Retained Earnings
Decrease to retained earnings	(6,744)					(6,318)					(6,744)		(6,318)		(5,928)	(5,543)
Impact on net income											593		541		521
Retained Earnings | Restatement Adjustment
Decrease to retained earnings																	3
Warrants | Recurring
Derivative assets	4					3					4		3
Residential mortgage
Past Due Threshold For Charge-Off											180 days
Consumer
Past Due Threshold For Charge-Off											120 days
Short-Cut Method | Designated as Hedging Instrument | Interest Rate Swaps | Fair Value Hedging
Notional Amount	$ 700	[1]									$ 700	[1]

[1] Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the consolidated balance sheets.

[2] Included $2 million of nonmarketable equity securities recorded at fair value on a nonrecurring basis at both December 31, 2014 and 2013.