Derivative Instruments - Notional Amount of Derivative Contracts (Details) - USD ($) $ in Billions	Jun. 30, 2015	Dec. 31, 2014
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	$ 53,708	$ 63,662
Interest rate contracts
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	38,753	48,085
Interest rate contracts | Swaps
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	23,790	29,734
Interest rate contracts | Futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	7,108	10,189
Interest rate contracts | Written options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	3,735	3,903
Interest rate contracts | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	4,120	4,259
Credit derivatives
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	3,681	4,249
Foreign exchange contracts
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	9,580	9,585
Foreign exchange contracts | Cross-currency swaps
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	3,262	3,346
Foreign exchange contracts | Spot, futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	4,810	4,669
Foreign exchange contracts | Written options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	750	790
Foreign exchange contracts | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	758	780
Equity contracts
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	1,067	1,063
Equity contracts | Swaps
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	237	206
Equity contracts | Futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	59	50
Equity contracts | Written options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	414	432
Equity contracts | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	357	375
Commodity contracts
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	627	680
Commodity contracts | Swaps
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	114	126
Commodity contracts | Spot, futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	162	193
Commodity contracts | Written options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	175	181
Commodity contracts | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Total derivative notional amounts	$ 176	$ 180