DERIVATIVES ACTIVITIES - Derivative Notionals (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Net Investment Hedging
Derivatives
Derivative notionals	$ 63	$ 1,825
Hedging instruments under ASC 815
Derivatives
Derivative notionals	270,445	227,616
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	189,779	151,428
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	189,779	151,331
Hedging instruments under ASC 815 | Interest rate futures and forwards
Derivatives
Derivative notionals	0	97
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	80,643	76,006
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	37,162	19,042
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	33,103	56,964
Hedging instruments under ASC 815 | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	3,951	0
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	6,427	0
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	23	182
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	23	182
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	45,671,920	45,753,242
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	31,910,784	31,699,124
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	18,718,224	19,145,250
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	6,447,886	6,864,276
Other derivative instruments, Trading derivatives | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	3,513,759	2,921,070
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	3,230,915	2,768,528
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	10,895,006	11,153,563
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	5,538,231	5,492,145
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	3,080,361	3,251,132
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,127,728	1,194,325
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,148,686	1,215,961
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,006,565	800,572
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	215,834	192,366
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	72,616	37,557
Other derivative instruments, Trading derivatives | Equity contract options | Written or Sold
Derivatives
Derivative notionals	389,961	304,579
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	328,154	266,070
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	357,858	357,560
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	82,039	70,774
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	153,248	142,530
Other derivative instruments, Trading derivatives | Commodity and other contract options | Written or Sold
Derivatives
Derivative notionals	62,045	74,627
Other derivative instruments, Trading derivatives | Commodity and other contract options | Purchased
Derivatives
Derivative notionals	60,526	69,629
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,501,707	1,742,423
Other derivative instruments, Trading derivatives | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	735,142	859,420
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	766,565	883,003
Other derivative instruments, Management hedges
Derivatives
Derivative notionals	120,743	135,802
Other derivative instruments, Management hedges | Interest rate contracts
Derivatives
Derivative notionals	54,130	90,237
Other derivative instruments, Management hedges | Interest rate swaps
Derivatives
Derivative notionals	35,995	47,324
Other derivative instruments, Management hedges | Interest rate futures and forwards
Derivatives
Derivative notionals	12,653	30,834
Other derivative instruments, Management hedges | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	2,372	4,759
Other derivative instruments, Management hedges | Interest rate contract options | Purchased
Derivatives
Derivative notionals	3,110	7,320
Other derivative instruments, Management hedges | Foreign exchange contracts
Derivatives
Derivative notionals	55,465	26,095
Other derivative instruments, Management hedges | Foreign exchange swaps
Derivatives
Derivative notionals	38,126	22,676
Other derivative instruments, Management hedges | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	17,339	3,419
Other derivative instruments, Management hedges | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Equity contracts
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Equity swaps
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Equity futures and forwards
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Equity contract options | Written or Sold
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Equity contract options | Purchased
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Commodity and other contracts
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Commodity and other swaps
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Commodity and other futures and forwards
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Commodity and other contract options | Written or Sold
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Commodity and other contract options | Purchased
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Credit derivatives
Derivatives
Derivative notionals	11,148	19,470
Other derivative instruments, Management hedges | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	0	0
Other derivative instruments, Management hedges | Credit derivatives | Purchased
Derivatives
Derivative notionals	$ 11,148	$ 19,470