CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (AOCI) - Change in Each Component of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	$ 202,672
Balance, end of period	198,353	$ 203,273
Discontinued Operations, Held-for-sale | Australia Consumer Banking Business
Change in accumulated other comprehensive income (loss)
Loss on sale of business, foreign currency translation adjustments, after-tax	475
Loss on sale of business, foreign currency translation adjustments	625
Net unrealized gains (losses) on debt securities
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(614)	3,320
Other comprehensive income before reclassifications	(4,283)	(1,519)
Increase (decrease) due to amounts reclassified from AOCI	6	(266)
Total other comprehensive income	(4,277)	(1,785)
Balance, end of period	(4,891)	1,535
Debt valuation adjustment (DVA)
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(1,187)	(1,419)
Other comprehensive income before reclassifications	793	(84)
Increase (decrease) due to amounts reclassified from AOCI	0	42
Total other comprehensive income	793	(42)
Balance, end of period	(394)	(1,461)
Cash flow hedges
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	101	1,593
Other comprehensive income before reclassifications	(1,324)	(344)
Increase (decrease) due to amounts reclassified from AOCI	(217)	(212)
Total other comprehensive income	(1,541)	(556)
Balance, end of period	(1,440)	1,037
Benefit plans
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(5,852)	(6,864)
Other comprehensive income before reclassifications	292	653
Increase (decrease) due to amounts reclassified from AOCI	(121)	61
Total other comprehensive income	171	714
Balance, end of period	(5,681)	(6,150)
Foreign currency translation adjustment (CTA), net of hedges
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(31,166)	(28,641)
Other comprehensive income before reclassifications	(14)	(1,274)
Increase (decrease) due to amounts reclassified from AOCI	0	0
Total other comprehensive income	(14)	(1,274)
Balance, end of period	(31,180)	(29,915)
Excluded component of fair value hedges
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(47)	(47)
Other comprehensive income before reclassifications	46	(10)
Increase (decrease) due to amounts reclassified from AOCI	2	0
Total other comprehensive income	48	(10)
Balance, end of period	1	(57)
Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss)
Balance, beginning of period	(38,765)	(32,058)
Other comprehensive income before reclassifications	(4,490)	(2,578)
Increase (decrease) due to amounts reclassified from AOCI	(330)	(375)
Total other comprehensive income	(4,820)	(2,953)
Balance, end of period	$ (43,585)	$ (35,011)