Financial Instruments (Derivatives and hedging) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 286,000
Derivative asset, fair value	1,117	3,557
Cumulative gain (loss) adjustment for non performance risk	(7)	(15)
Excess Collateralization	160	42
Excess Collateral Posted	37	10
Excess Securities Collateral Held	286	359
Netting Adjustment Including Collateral [Member] | Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(6,546)	(7,657)
Derivative liabilities	(4,162)	(2,908)
Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	8,890	12,897
Derivative liabilities	5,150	3,074
Netting Adjustment [Member] | Amounts Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(3,927)	(2,532)
Derivative liabilities	(3,920)	(2,517)
Cash Collateral [Member] | Amounts Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(2,619)	(5,125)
Derivative liabilities	(242)	(391)
Securities Pledged as Collateral [Member] | Not Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(1,838)	(5,060)
Derivative liabilities	0	0
Derivatives Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	5,583	9,270
Derivative liabilities	2,947	2,481
Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	2,080	1,944
Derivative liabilities	1,962	579
Derivatives Associated With Interest Rate, Currency Or Market Risk Reduction Or Elimination [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	277,000
Percentage Of Notional Amount That Is Associated With Reducing Or Eliminating Interest Rate, Currency, Or Market Risk	97.00%
Gross Derivatives [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	7,663	11,214
Derivative liabilities	4,909	3,060
Gross Accrued Interest [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	1,227	1,683
Derivative liabilities	241	14
Net Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	506	180
Derivative liability, fair value	988	166
Net Derivative [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	2,344	5,240
Derivative liabilities	988	166
Interest Rate Contract [Member] | Derivatives Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	3,837	8,443
Derivative liabilities	1,989	719
Interest Rate Contract [Member] | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	270	452
Derivative liabilities	175	195
Foreign Exchange Contract [Member] | Derivatives Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	1,746	827
Derivative liabilities	958	1,762
Foreign Exchange Contract [Member] | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	1,753	1,457
Derivative liabilities	1,765	358
Other Contract [Member] | Derivatives Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Other Contract [Member] | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	57	35
Derivative liabilities	$ 22	$ 26