DERIVATIVES ACTIVITIES - Derivative Notionals (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Hedging instruments under ASC 815
Derivatives
Derivative notionals	$ 344,178	$ 270,445
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	246,079	189,779
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	246,079	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	97,702	80,643
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	54,502	37,162
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	37,769	33,103
Hedging instruments under ASC 815 | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	2,497	3,951
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	2,934	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	397	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	397	23
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	54,318,541	45,792,663
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	35,152,101	31,964,914
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	19,759,439	18,754,219
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	8,297,965	6,460,539
Other derivative instruments, Trading derivatives | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	3,857,773	3,516,131
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	3,236,924	3,234,025
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	16,139,406	10,950,471
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	7,004,521	5,576,357
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	5,711,577	3,097,700
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,727,916	1,127,728
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,695,392	1,148,686
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,085,173	1,006,565
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	245,167	215,834
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	70,526	72,616
Other derivative instruments, Trading derivatives | Equity contract options | Written or Sold
Derivatives
Derivative notionals	436,032	389,961
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	333,448	328,154
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	425,009	357,858
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	118,699	82,039
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	164,427	153,248
Other derivative instruments, Trading derivatives | Commodity and other contracts | Written or Sold
Derivatives
Derivative notionals	72,021	62,045
Other derivative instruments, Trading derivatives | Commodity and other contracts | Purchased
Derivatives
Derivative notionals	69,862	60,526
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,516,852	1,512,855
Other derivative instruments, Trading derivatives | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	723,060	735,142
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	$ 793,792	$ 777,713