Derivative Financial Instruments (Derivative Classifications and Hedging Relationships) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative financial instruments, notional values	$ 61,504	$ 59,318
Total derivative asset	894	864
Amounts subject to master netting arrangements not offset due to policy election, assets column	(516)	(514)
Cash collateral (received) posted	(66)	(44)
Net amount	312	306
Total derivative liability	(839)	(970)
Amounts subject to master netting arrangements not offset due to policy election, liabilities column	516	514
Cash collateral (received) posted	277	386
Net amount	(46)	(70)
Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Pay Fixed Swaps [Member] | Three Month LIBOR Funding [Member]
Derivative financial instruments, notional values	8,150	4,300
Total derivative asset	0	0
Total derivative liability	(186)	(203)
Fair Value Hedges [Member] | Interest Rate Contract [Member]
Derivative financial instruments, notional values	9,577	7,345
Total derivative asset	197	102
Total derivative liability	(113)	(89)
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Received Fixed Swaps And Option Trades [Member] | Long-term Debt [Member]
Derivative financial instruments, notional values	9,052	6,822
Total derivative asset	197	102
Total derivative liability	(2)	(3)
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Pay Fixed Swaps [Member] | Commercial Loans [Member]
Derivative financial instruments, notional values	179	178
Total derivative asset	0	0
Total derivative liability	(3)	(3)
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Pay Fixed Swaps [Member] | Municipal Securities [Member]
Derivative financial instruments, notional values	346	345
Total derivative asset	0	0
Total derivative liability	(108)	(83)
Not Designated as Hedging Instrument [Member]
Derivative financial instruments, notional values	43,777	47,673
Total derivative asset	697	762
Total derivative liability	(540)	(678)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member]
Derivative financial instruments, notional values	18,629	19,414
Total derivative asset	390	411
Total derivative liability	(422)	(446)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Interest Rate Contract [Member] | Receive Fixed Swaps [Member]
Derivative financial instruments, notional values	8,140	8,619
Total derivative asset	375	370
Total derivative liability	(8)	(37)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Interest Rate Contract [Member] | Pay Fixed Swaps [Member]
Derivative financial instruments, notional values	8,019	8,401
Total derivative asset	6	31
Total derivative liability	(401)	(396)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Interest Rate Contract [Member] | Other Swaps [Member]
Derivative financial instruments, notional values	1,469	1,586
Total derivative asset	6	6
Total derivative liability	(8)	(8)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Interest Rate Contract [Member] | Other [Member]
Derivative financial instruments, notional values	557	424
Total derivative asset	1	2
Total derivative liability	(1)	(2)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Foreign Exchange Contract [Member]
Derivative financial instruments, notional values	444	384
Total derivative asset	2	2
Total derivative liability	(4)	(3)
Not Designated as Hedging Instrument [Member] | Mortgage Banking [Member] | Interest Rate Contract [Member]
Derivative financial instruments, notional values	7,383	5,500
Total derivative asset	35	45
Total derivative liability	(44)	(28)
Not Designated as Hedging Instrument [Member] | Mortgage Banking [Member] | Interest Rate Contract [Member] | Interest Rate Lock Commitments [Member]
Derivative financial instruments, notional values	2,593	1,869
Total derivative asset	25	3
Total derivative liability	0	(14)
Not Designated as Hedging Instrument [Member] | Mortgage Banking [Member] | Interest Rate Contract [Member] | When Issued Securities And Forward Rate Agreements And Forward Commitments [Member]
Derivative financial instruments, notional values	3,823	3,100
Total derivative asset	5	34
Total derivative liability	(43)	(7)
Not Designated as Hedging Instrument [Member] | Mortgage Banking [Member] | Interest Rate Contract [Member] | Other [Member]
Derivative financial instruments, notional values	967	531
Total derivative asset	5	8
Total derivative liability	(1)	(7)
Not Designated as Hedging Instrument [Member] | MSRs [Member] | Interest Rate Contract [Member]
Derivative financial instruments, notional values	17,765	22,759
Total derivative asset	272	306
Total derivative liability	(74)	(204)
Not Designated as Hedging Instrument [Member] | MSRs [Member] | Interest Rate Contract [Member] | Receive Fixed Swaps [Member]
Derivative financial instruments, notional values	2,555	6,139
Total derivative asset	85	36
Total derivative liability	(7)	(141)
Not Designated as Hedging Instrument [Member] | MSRs [Member] | Interest Rate Contract [Member] | Pay Fixed Swaps [Member]
Derivative financial instruments, notional values	2,611	5,449
Total derivative asset	7	89
Total derivative liability	(39)	(29)
Not Designated as Hedging Instrument [Member] | MSRs [Member] | Interest Rate Contract [Member] | Option Trades [Member]
Derivative financial instruments, notional values	8,495	9,415
Total derivative asset	173	181
Total derivative liability	(27)	(31)
Not Designated as Hedging Instrument [Member] | MSRs [Member] | Interest Rate Contract [Member] | When Issued Securities And Forward Rate Agreements And Forward Commitments [Member]
Derivative financial instruments, notional values	4,104	1,756
Total derivative asset	7	0
Total derivative liability	$ (1)	$ (3)