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VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Variable Interest Entity
Lending to special purpose entities included in loans and leases	$ 131,305,000,000		$ 128,163,000,000
LIHTC Investments
Variable Interest Entity
Net impairment losses recognized in earnings	0	$ 0
Commitments to extend credit \| Special Purpose Entities
Variable Interest Entity
Commitment amount	2,100,000,000		1,900,000,000
Commercial and industrial \| Special Purpose Entities
Variable Interest Entity
Lending to special purpose entities included in loans and leases	2,602,000,000		2,646,000,000
Retail
Variable Interest Entity
Lending to special purpose entities included in loans and leases	69,784,000,000		67,813,000,000
Retail \| Education
Variable Interest Entity
Lending to special purpose entities included in loans and leases	$ 13,306,000,000		$ 12,997,000,000