ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward by Segment (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	$ 16,455	$ 24,956
Gross credit losses on loans	(1,240)	(2,208)
Gross recoveries on loans	368	460
Replenishment of NCLs	872	1,748
Net reserve builds (releases)	(781)	(3,068)
Net specific reserve builds (releases)	169	(159)
Other	(450)	(91)
ACLL at end of period	15,393	21,638
ACLL
Collectively evaluated	14,369		$ 15,430
Individually evaluated	1,025		1,025
Total ACLL	15,393	21,638	16,455
Loans, net of unearned income
Collectively evaluated	648,865		656,265
Individually evaluated	4,960		5,301
Loans held at fair value	5,732		6,082
Total loans, net of unearned income	659,669		667,767
Purchased credit deteriorated
ACLL
Purchased credit deteriorated	(1)		0
Loans, net of unearned income
Purchased credit deteriorated	112		119
Corporate
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	2,415	4,776
Gross credit losses on loans	(48)	(199)
Gross recoveries on loans	17	14
Replenishment of NCLs	31	185
Net reserve builds (releases)	376	(1,193)
Net specific reserve builds (releases)	225	(34)
Other	9	(7)
ACLL at end of period	3,025	3,542
ACLL
Collectively evaluated	2,586		2,203
Individually evaluated	439		212
Total ACLL	3,025	3,542	2,415
Loans, net of unearned income
Collectively evaluated	301,753		283,610
Individually evaluated	1,866		1,553
Loans held at fair value	5,722		6,070
Total loans, net of unearned income	309,341		291,233
Corporate \| Purchased credit deteriorated
ACLL
Purchased credit deteriorated	0		0
Loans, net of unearned income
Purchased credit deteriorated	0		0
Consumer
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	14,040	20,180
Gross credit losses on loans	(1,192)	(2,009)
Gross recoveries on loans	351	446
Replenishment of NCLs	841	1,563
Net reserve builds (releases)	(1,157)	(1,875)
Net specific reserve builds (releases)	(56)	(125)
Other	(459)	(84)
ACLL at end of period	12,368	18,096
ACLL
Collectively evaluated	11,783		13,227
Individually evaluated	586		813
Total ACLL	12,368	$ 18,096	14,040
Loans, net of unearned income
Collectively evaluated	347,112		372,655
Individually evaluated	3,094		3,748
Loans held at fair value	10		12
Total loans, net of unearned income	350,328		376,534
Consumer \| Purchased credit deteriorated
ACLL
Purchased credit deteriorated	(1)		0
Loans, net of unearned income
Purchased credit deteriorated	$ 112		$ 119

Financing Receivable, Allowance For Credit Loss, Adjustments, Other

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Provision charged or released during the period against earnings for credit losses on loans and leases receivable that are expected and were collectively evaluated for impairment.

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Provision charged or released during the period against earnings for credit losses on loans and leases receivable that are expected and were individually evaluated for impairment.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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