DERIVATIVES ACTIVITIES - Derivative Notionals (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Hedging instruments under ASC 815
Derivatives
Derivative notionals	$ 376,831	$ 270,445
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	273,636	189,779
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	273,636	189,779
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	102,393	80,643
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	57,153	37,162
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	41,410	33,103
Hedging instruments under ASC 815 | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,726	3,951
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	2,104	6,427
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	802	23
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	802	23
Hedging instruments under ASC 815 | Commodity and other contract options | Written or Sold
Derivatives
Derivative notionals	0	0
Hedging instruments under ASC 815 | Commodity and other contract options | 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	46,221,407	45,783,055
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	28,321,891	31,964,914
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	18,138,686	18,754,219
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	4,632,257	6,460,539
Other derivative instruments, Trading derivatives | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	3,018,469	3,516,131
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	2,532,479	3,234,025
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	14,963,895	10,950,471
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	6,738,158	5,576,357
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	5,115,504	3,097,700
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,566,717	1,127,728
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,543,516	1,148,686
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,065,326	1,006,565
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	217,580	215,834
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	52,053	72,616
Other derivative instruments, Trading derivatives | Equity contract options | Written or Sold
Derivatives
Derivative notionals	454,675	389,961
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	341,018	328,154
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	349,707	348,250
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	79,133	72,431
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	146,647	153,248
Other derivative instruments, Trading derivatives | Commodity and other contract options | Written or Sold
Derivatives
Derivative notionals	62,629	62,045
Other derivative instruments, Trading derivatives | Commodity and other contract options | Purchased
Derivatives
Derivative notionals	61,298	60,526
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,520,588	1,512,855
Other derivative instruments, Trading derivatives | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	724,939	735,142
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	$ 795,649	$ 777,713