Derivative Instruments and Hedging Activities - Notional and Fair Values of Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	$ 81,451	$ 63,424
Derivative Assets	836	959
Derivative Liabilities	369	710
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	50,387	33,326
Derivative Assets	460	338
Derivative Liabilities	170	425
Derivatives designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	43,108	28,520
Derivative Assets	218	289
Derivative Liabilities	170	372
Derivatives designated as accounting hedges | Interest rate contracts | Fair value hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	23,008	15,695
Derivative Assets	214	289
Derivative Liabilities	105	223
Derivatives designated as accounting hedges | Interest rate contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	20,100	12,825
Derivative Assets	4	0
Derivative Liabilities	65	149
Derivatives designated as accounting hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	7,279	4,806
Derivative Assets	242	49
Derivative Liabilities	0	53
Derivatives designated as accounting hedges | Foreign exchange contracts | Cash flow hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	4,860	4,806
Derivative Assets	129	49
Derivative Liabilities	0	53
Derivatives designated as accounting hedges | Foreign exchange contracts | Net investment hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,419	0
Derivative Assets	113	0
Derivative Liabilities	0	0
Derivatives not designated as accounting hedges
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	31,064	30,098
Derivative Assets	376	621
Derivative Liabilities	199	285
Derivatives not designated as accounting hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	30,348	27,582
Derivative Assets	371	434
Derivative Liabilities	186	233
Derivatives not designated as accounting hedges | Interest rate contracts | MSRs
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	483	353
Derivative Assets	2	0
Derivative Liabilities	1	7
Derivatives not designated as accounting hedges | Interest rate contracts | Customer accommodation
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	27,208	25,365
Derivative Assets	338	405
Derivative Liabilities	168	209
Derivatives not designated as accounting hedges | Interest rate contracts | Other interest rate exposures
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	2,657	1,864
Derivative Assets	31	29
Derivative Liabilities	17	17
Derivatives not designated as accounting hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	190	1,422
Derivative Assets	5	184
Derivative Liabilities	0	37
Derivatives not designated as accounting hedges | Other contracts
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	526	1,094
Derivative Assets	0	3
Derivative Liabilities	$ 13	$ 15