Financial Instruments (Derivatives and hedging) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 341,000
Derivative asset, fair value	373	1,005
Derivative liability, fair value	376	1,315
Cumulative gain (loss) adjustment for non performance risk	20	(7)
Excess Collateralization	81	160
Excess Collateral Posted	93	37
Excess Securities Collateral Held	110	363
Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	10,682	9,706
Derivative liabilities	4,265	5,670
Netting Adjustment [Member] | Derivatives
Derivatives, Fair Value [Line Items]
Derivative assets	(7,186)	(6,739)
Derivative liabilities	(3,889)	(4,355)
Netting Adjustment [Member] | Amounts Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(3,586)	(4,120)
Derivative liabilities	(3,606)	(4,113)
Cash Collateral [Member] | Amounts Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(3,600)	(2,619)
Derivative liabilities	(283)	(242)
Securities Pledged as Collateral [Member] | Not Offset In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(3,123)	(1,962)
Derivative liabilities	0	0
Derivatives Accounted For As Hedges
Derivatives, Fair Value [Line Items]
Derivative assets	7,103	5,668
Derivative liabilities	1,402	2,973
Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	2,379	2,811
Derivative liabilities	2,828	2,456
Derivatives Associated With Interest Rate, Currency Or Market Risk Reduction Or Elimination [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	301,000
Percentage Of Notional Amount That Is Associated With Reducing Or Eliminating Interest Rate, Currency, Or Market Risk	88.00%
Gross Derivatives [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	9,482	8,479
Derivative liabilities	4,230	5,429
Gross Accrued Interest [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	1,200	1,227
Derivative liabilities	35	241
Net Derivative [Member] | Recognized In Statement Of Financial Position [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	3,496	2,967
Derivative liabilities	376	1,315
Interest Rate Contract | Derivatives Accounted For As Hedges
Derivatives, Fair Value [Line Items]
Derivative assets	4,630	3,837
Derivative liabilities	874	1,989
Interest Rate Contract | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	256	270
Derivative liabilities	139	169
Foreign Exchange Contract | Derivatives Accounted For As Hedges
Derivatives, Fair Value [Line Items]
Derivative assets	2,473	1,830
Derivative liabilities	528	984
Foreign Exchange Contract | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	1,888	2,257
Derivative liabilities	2,644	2,245
Other Contract | Derivatives Accounted For As Hedges
Derivatives, Fair Value [Line Items]
Derivative assets	0	1
Derivative liabilities	0	0
Other Contract | Derivatives Not Accounted For As Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	235	284
Derivative liabilities	$ 45	$ 42