CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Change in Each Component of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Change in accumulated other comprehensive income (loss)
Balance, beginning of period				$ 223,092
Balance, end of period		$ 232,690	$ 222,137	232,690	$ 222,137
Net unrealized gains (losses) on investment securities
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		2,054	(287)	(907)	57
Adjustment to opening balance, net of taxes						$ 0
Adjusted balance, beginning of period				(907)
Other comprehensive income before reclassifications		(270)	556	2,781	453
Increase (decrease) due to amounts reclassified from AOCI		(162)	(45)	(252)	(286)
Change, net of taxes		(432)	511	2,529	167
Balance, end of period		1,622	224	1,622	224
Debt valuation adjustment (DVA)
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		190		0
Adjustment to opening balance, net of taxes						(15)
Adjusted balance, beginning of period				(15)
Other comprehensive income before reclassifications		(197)		11
Increase (decrease) due to amounts reclassified from AOCI		(3)		(6)
Change, net of taxes		(200)		5
Balance, end of period		(10)		(10)
Cash flow hedges
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		(149)	(731)	(617)	(909)
Adjustment to opening balance, net of taxes						0
Adjusted balance, beginning of period				(617)
Other comprehensive income before reclassifications		(136)	149	270	203
Increase (decrease) due to amounts reclassified from AOCI		53	40	115	164
Change, net of taxes		(83)	189	385	367
Balance, end of period		(232)	(542)	(232)	(542)
Benefit plans
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		(5,608)	(4,671)	(5,116)	(5,159)
Adjustment to opening balance, net of taxes						0
Adjusted balance, beginning of period				(5,116)
Other comprehensive income before reclassifications		(28)	(400)	(594)	7
Increase (decrease) due to amounts reclassified from AOCI		40	40	114	121
Change, net of taxes		12	(360)	(480)	128
Balance, end of period		(5,596)	(5,031)	(5,596)	(5,031)
Foreign currency translation adjustment (CTA), net of hedges
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		(22,602)	(19,415)	(22,704)	(17,205)
Adjustment to opening balance, net of taxes						0
Adjusted balance, beginning of period				(22,704)
Other comprehensive income before reclassifications		(375)	(2,493)	(273)	(4,703)
Increase (decrease) due to amounts reclassified from AOCI		0	0	0	0
Change, net of taxes		(375)	(2,493)	(273)	(4,703)
Balance, end of period		(22,977)	(21,908)	(22,977)	(21,908)
Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		(26,115)	(25,104)	(29,344)	(23,216)
Adjustment to opening balance, net of taxes	[1]					$ (15)	$ 0
Adjusted balance, beginning of period				(29,359)	(23,216)
Other comprehensive income before reclassifications		(1,006)	(2,188)	2,195	(4,040)
Increase (decrease) due to amounts reclassified from AOCI		(72)	35	(29)	(1)
Change, net of taxes		(1,078)	(2,153)	2,166	(4,041)
Balance, end of period		$ (27,193)	$ (27,257)	$ (27,193)	$ (27,257)

[1] See Note 1 to the Consolidated Financial Statements for additional details.