DERIVATIVES - Derivative Notionals (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Hedging instruments under ASC 815
Derivatives
Derivative notionals	$ 416,343	$ 420,823
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	311,333	318,089
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	311,333	318,089
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 or Sold
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	104,116	101,539
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	65,358	63,104
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	38,597	38,275
Hedging instruments under ASC 815 | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	116	80
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	45	80
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 or Sold
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	894	1,195
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	894	1,195
Hedging instruments under ASC 815 | Commodity and other contracts | Written or Sold
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 or Sold
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	43,568,043	39,522,192
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	27,024,356	24,672,211
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	18,935,609	17,063,272
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	4,691,885	3,636,658
Other derivative instruments, Trading derivatives | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	1,791,782	2,114,511
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	1,605,080	1,857,770
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	13,663,620	11,910,251
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	6,414,190	6,063,853
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	4,806,697	3,979,188
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,209,072	908,061
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,233,661	959,149
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,163,309	1,247,562
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	168,224	197,893
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	60,692	66,705
Other derivative instruments, Trading derivatives | Equity contract options | Written or Sold
Derivatives
Derivative notionals	534,464	560,571
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	399,929	422,393
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	397,477	384,855
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	74,616	69,445
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	141,378	137,192
Other derivative instruments, Trading derivatives | Commodity and other contracts | Written or Sold
Derivatives
Derivative notionals	91,874	91,587
Other derivative instruments, Trading derivatives | Commodity and other contracts | Purchased
Derivatives
Derivative notionals	89,609	86,631
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,319,281	1,307,313
Other derivative instruments, Trading derivatives | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	624,063	603,387
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	695,218	703,926
Rule Changes Adopted by Clearing Organizations
Derivatives
Reduction in derivative receivables	$ 300,000	$ 180,000