CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Change in Each Compenant of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	$ (25,104)	$ (18,147)	$ (23,216)	$ (19,133)	$ (19,133)
End-of-period balance, net of tax	(27,257)	(19,976)	(27,257)	(19,976)	(23,216)
Net unrealized gains (losses) on investment securities
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	(287)	(206)	57	(1,640)	(1,640)
Other comprehensive income (losses) before reclassifications	556	(173)	453	1,242
Increase (decrease) due to amounts reclassified from AOCI	(45)	(34)	(286)	(15)
Change, net of taxes	511	(207)	167	1,227
End-of-period balance, net of tax	224	(413)	224	(413)	57
Cash flow hedges
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	(731)	(1,007)	(909)	(1,245)	(1,245)
Other comprehensive income (losses) before reclassifications	149	(42)	203	62
Increase (decrease) due to amounts reclassified from AOCI	40	70	164	204
Change, net of taxes	189	28	367	266
End-of-period balance, net of tax	(542)	(979)	(542)	(979)	(909)
Benefit plans
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	(4,671)	(4,166)	(5,159)	(3,989)	(3,989)
Other comprehensive income (losses) before reclassifications	(400)	17	7	(240)
Increase (decrease) due to amounts reclassified from AOCI	40	54	121	134
Change, net of taxes	(360)	71	128	(106)
End-of-period balance, net of tax	(5,031)	(4,095)	(5,031)	(4,095)	(5,159)
Foreign currency translation adjustment, net of hedges
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	(19,415)	(12,768)	(17,205)	(12,259)	(12,259)
Other comprehensive income (losses) before reclassifications	(2,493)	(1,721)	(4,703)	(2,230)
Increase (decrease) due to amounts reclassified from AOCI	0	0	0	0
Change, net of taxes	(2,493)	(1,721)	(4,703)	(2,230)
End-of-period balance, net of tax	(21,908)	(14,489)	(21,908)	(14,489)	(17,205)
Reclassification for allocation between net unrealized gains (losses) on investment securities to CTA, before tax					137
Reclassification for allocation between net unrealized gains (losses) on investment securities to CTA, net of tax					84
Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	(25,104)	(18,147)	(23,216)	(19,133)	(19,133)
Other comprehensive income (losses) before reclassifications	(2,188)	(1,919)	(4,040)	(1,166)
Increase (decrease) due to amounts reclassified from AOCI	35	90	(1)	323
Change, net of taxes	(2,153)	(1,829)	(4,041)	(843)
End-of-period balance, net of tax	$ (27,257)	$ (19,976)	$ (27,257)	$ (19,976)	$ (23,216)