DERIVATIVES ACTIVITIES - Derivative Notionals (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Net Investment Hedging
Derivatives
Derivative notionals	$ 2	$ 63
Hedging instruments under ASC 815
Derivatives
Derivative notionals	279,640	270,445
Hedging instruments under ASC 815 | Interest rate contracts
Derivatives
Derivative notionals	197,828	189,779
Hedging instruments under ASC 815 | Interest rate swaps
Derivatives
Derivative notionals	197,328	189,779
Hedging instruments under ASC 815 | Interest rate futures and forwards
Derivatives
Derivative notionals	500	0
Hedging instruments under ASC 815 | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	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	81,721	80,643
Hedging instruments under ASC 815 | Foreign exchange swaps
Derivatives
Derivative notionals	40,063	37,162
Hedging instruments under ASC 815 | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	39,102	33,103
Hedging instruments under ASC 815 | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,151	3,951
Hedging instruments under ASC 815 | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,405	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	91	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	91	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	55,216,776	45,792,663
Other derivative instruments, Trading derivatives | Interest rate contracts
Derivatives
Derivative notionals	37,856,351	31,964,914
Other derivative instruments, Trading derivatives | Interest rate swaps
Derivatives
Derivative notionals	21,321,930	18,754,219
Other derivative instruments, Trading derivatives | Interest rate futures and forwards
Derivatives
Derivative notionals	8,245,034	6,460,539
Other derivative instruments, Trading derivatives | Interest rate contract options | Written or Sold
Derivatives
Derivative notionals	4,578,837	3,516,131
Other derivative instruments, Trading derivatives | Interest rate contract options | Purchased
Derivatives
Derivative notionals	3,710,550	3,234,025
Other derivative instruments, Trading derivatives | Foreign exchange contracts
Derivatives
Derivative notionals	14,317,143	10,950,471
Other derivative instruments, Trading derivatives | Foreign exchange swaps
Derivatives
Derivative notionals	6,940,579	5,576,357
Other derivative instruments, Trading derivatives | Foreign exchange futures, forwards and spot
Derivatives
Derivative notionals	4,465,416	3,097,700
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Written or Sold
Derivatives
Derivative notionals	1,460,614	1,127,728
Other derivative instruments, Trading derivatives | Foreign exchange contract options | Purchased
Derivatives
Derivative notionals	1,450,534	1,148,686
Other derivative instruments, Trading derivatives | Equity contracts
Derivatives
Derivative notionals	1,105,494	1,006,565
Other derivative instruments, Trading derivatives | Equity swaps
Derivatives
Derivative notionals	243,567	215,834
Other derivative instruments, Trading derivatives | Equity futures and forwards
Derivatives
Derivative notionals	67,910	72,616
Other derivative instruments, Trading derivatives | Equity contract options | Written or Sold
Derivatives
Derivative notionals	427,798	389,961
Other derivative instruments, Trading derivatives | Equity contract options | Purchased
Derivatives
Derivative notionals	366,219	328,154
Other derivative instruments, Trading derivatives | Commodity and other contracts
Derivatives
Derivative notionals	405,954	357,858
Other derivative instruments, Trading derivatives | Commodity and other swaps
Derivatives
Derivative notionals	92,552	82,039
Other derivative instruments, Trading derivatives | Commodity and other futures and forwards
Derivatives
Derivative notionals	176,174	153,248
Other derivative instruments, Trading derivatives | Commodity and other contracts | Written or Sold
Derivatives
Derivative notionals	71,136	62,045
Other derivative instruments, Trading derivatives | Commodity and other contracts | Purchased
Derivatives
Derivative notionals	66,092	60,526
Other derivative instruments, Trading derivatives | Credit derivatives
Derivatives
Derivative notionals	1,531,834	1,512,855
Other derivative instruments, Trading derivatives | Credit derivatives | Written or Sold
Derivatives
Derivative notionals	741,700	735,142
Other derivative instruments, Trading derivatives | Credit derivatives | Purchased
Derivatives
Derivative notionals	$ 790,134	$ 777,713