SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Changes Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	3 Months Ended				12 Months Ended
		Jan. 01, 2020	Jan. 31, 2023	Jun. 30, 2022	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2023	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle
Decrease in interest expense								$ (11,559)	$ (2,896)	$ (5,334)
Increase in other operating expenses								12,174	11,427	11,227
Increase (decrease) in allowance for credit losses								16,974	16,455	24,956		$ 16,541
Pretax percentage increase allowance for credit losses		29.00%
Increase (decrease) in retained earnings								194,734	184,948
Increase (decrease) in deferred tax assets								27,672	24,789
Build to allowance for credit losses								937	(7,283)	7,635
Increase (decrease) in provisions for credit losses on loans								4,745	(3,103)	15,922
Increase in operating expenses								51,292	48,193	44,374
Decrease in net income								$ (14,845)	$ (21,952)	$ (11,047)
Decrease in net income (in dollars per share)	[1]							$ (7.04)	$ (10.21)	$ (4.74)
Increase (decrease) in other assets								$ 103,743	$ 101,551
Purchase of investments, operating activities									(2,000)	$ (30)
Impact to cash from (used in) operating activities	[2]							25,069	47,090	(23,488)
Impact to cash from (used in) investing activities	[2]							79,455	110,746	92,445
Macroeconomic Uncertainty
New Accounting Pronouncements or Change in Accounting Principle
Decrease in allowance for credit losses				$ (800)
Change in Accounting Method Accounted for as Change in Estimate
New Accounting Pronouncements or Change in Accounting Principle
Decrease in allowance for credit losses				$ 300
Subsequent event
New Accounting Pronouncements or Change in Accounting Principle
HTM securities, amortized cost, transferred to AFS			$ 3,300
HTM securities, fair value, transferred to AFS			$ 3,400
Cumulative effect of adoption
New Accounting Pronouncements or Change in Accounting Principle
Increase (decrease) in allowance for credit losses		$ 4,100									$ (350)	4,201
Increase (decrease) in retained earnings		(3,100)									300
Increase (decrease) in deferred tax assets		1,000
Build to allowance for credit losses		4,900
Release of reserves		$ 800
Increase (decrease) in deferred income tax assets											(100)
Increase (decrease) in other assets											$ 50
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle
Loss coverage period		23 months
Accounting Guidance Prior to Adoption of ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle
Loss coverage period		14 months
Reclassification adjustment
New Accounting Pronouncements or Change in Accounting Principle
Decrease in interest expense								1,207	1,203	781
Increase in other operating expenses								$ 1,207	1,203	781
Impact to cash from (used in) operating activities									2,000	30
Impact to cash from (used in) investing activities									$ 2,000	30
Variable post-charge-off third-party collection costs
New Accounting Pronouncements or Change in Accounting Principle
Increase (decrease) in allowance for credit losses		$ (443)			$ (122)	$ (426)						$ (443)
Increase (decrease) in retained earnings		$ 330
Increase (decrease) in provisions for credit losses on loans					$ 122	339	$ (18)
Increase in operating expenses						$ 45	$ 49
Decrease in net income										$ 330
Decrease in net income (in dollars per share)										$ 0.16

[1] Due to rounding, earnings per share on continuing operations and discontinued operations may not sum to earnings per share on net income.

[2] See “Statement of Cash Flows” in Note 1.