Derivative Instruments - Notional Amount of Derivative Contracts (Details) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	$ 47,194	$ 46,942
Interest rate contracts
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	31,093	32,679
Swaps
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	20,986	21,228
Futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	3,057	3,152
Options | Written options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	3,375	3,938
Options | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	3,675	4,361
Net credit derivatives
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	1,201	1,242
Foreign exchange contracts
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	12,450	10,599
Cross-currency swaps
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	3,924	3,604
Spot, futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	6,871	5,577
Options | Written options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	830	700
Options | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	825	718
Equity contracts
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	1,885	1,805
Swaps
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	448	406
Futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	140	142
Options | Written options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	676	646
Options | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	621	611
Commodity contracts
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	565	617
Swaps
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	138	147
Spot, futures and forwards
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	198	211
Options | Written options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	124	135
Options | Purchased options
Notional amount of derivative contracts outstanding [Abstract]
Derivative notional amounts	$ 105	$ 124