DERIVATIVES - Derivative Notionals (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Hedging instruments under ASC 815
Derivatives
Derivative notionals	$ 390,124	$ 438,164
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	283,433	334,351
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	283,433	334,351
Hedging instruments under ASC 815 | Interest rate futures and forwards
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Interest rate contract options | Written
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Interest rate contract options | Purchased
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Foreign exchange contracts
Derivatives
Derivative notionals	104,349	102,889
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	50,214	65,709
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	54,135	37,080
Hedging instruments under ASC 815 | Foreign exchange contract options | Written
Derivatives
Derivative notionals	0	47
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	0	53
Hedging instruments under ASC 815 | Equity contracts
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Equity swaps
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Equity futures and forwards
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Equity contract options | Written
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Equity contract options | Purchased
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Commodity and other contracts
Derivatives
Derivative notionals	2,342	924
Hedging instruments under ASC 815 | Commodity and other swaps
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Commodity and other futures and forwards
Derivatives
Derivative notionals	2,342	924
Hedging instruments under ASC 815 | Commodity and other contracts | Written
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Commodity and other contracts | Purchased
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Credit derivatives
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Credit derivatives | Written
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Credit derivatives | Purchased
Derivatives
Derivative notionals	0	0
Other derivative instruments, Trading derivatives
Derivatives
Derivative notionals	42,900,306	39,808,290
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	26,729,481	24,858,399
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	20,154,428	17,724,147
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	3,485,545	4,142,514
Other derivative instruments, Trading derivatives | Interest rate contract options | Written
Derivatives
Derivative notionals	1,619,341	1,573,483
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	1,470,167	1,418,255
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	12,972,625	12,320,659
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	6,707,996	6,567,304
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	4,778,312	3,945,391
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written
Derivatives
Derivative notionals	746,078	907,338
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	740,239	900,626
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,464,682	1,110,328
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	313,557	274,098
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	92,136	67,025
Other derivative instruments, Trading derivatives | Equity contract options | Written
Derivatives
Derivative notionals	585,440	441,003
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	473,549	328,202
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	393,431	362,527
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	94,768	80,127
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	176,408	143,175
Other derivative instruments, Trading derivatives | Commodity and other contracts | Written
Derivatives
Derivative notionals	63,308	71,376
Other derivative instruments, Trading derivatives | Commodity and other contracts | Purchased
Derivatives
Derivative notionals	58,947	67,849
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,340,087	1,156,377
Other derivative instruments, Trading derivatives | Credit derivatives | Written
Derivatives
Derivative notionals	634,497	543,607
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	705,590	612,770
Rule Changes Adopted by Clearing Organizations
Derivatives
Reduction in derivative receivables	$ 290,000	$ 280,000