FAIR VALUE MEASUREMENT - Valuation Techniques and Inputs for Level 3 Nonrecurring Fair Value Measurements (Details) - Nonrecurring	3 Months Ended		6 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($) decimal
Nonrecurring fair value changes included in earnings
Nonrecurring fair value measurements included in earnings	$ (93,000,000)	$ (16,000,000)	$ (119,000,000)	$ (91,000,000)
Level 3
Valuation techniques and inputs
Loans HFS	580,000,000		580,000,000		$ 453,000,000
Loans					271,000,000
Price-based \| Level 3
Valuation techniques and inputs
Non-marketable equities	152,000,000		152,000,000		254,000,000
Price-based \| Level 3 \| Minimum
Valuation techniques and inputs
Loans HFS	$ 579,000,000		$ 579,000,000		$ 453,000,000
Price-based \| Price \| Level 3 \| Minimum
Valuation techniques and inputs
Loans HFS	84.96		84.96		83.00
Non-marketable equities	1.71		1.71		4.57
Price-based \| Price \| Level 3 \| Maximum
Valuation techniques and inputs
Loans HFS	100.11		100.11		100.00
Non-marketable equities	347.33		347.33		205.01
Price-based \| Price \| Level 3 \| Weighted Average
Valuation techniques and inputs
Loans HFS	92.07		92.07		98.66
Non-marketable equities	87.90		87.90		70.91
Recovery analysis \| Level 3
Valuation techniques and inputs
Loans	$ 135,000,000		$ 135,000,000
Recovery analysis \| Appraised value \| Level 3 \| Minimum
Valuation techniques and inputs
Loans	14,750		14,750		10,000
Recovery analysis \| Appraised value \| Level 3 \| Maximum
Valuation techniques and inputs
Loans	23,243,563		23,243,563		75,424,500
Recovery analysis \| Appraised value \| Level 3 \| Weighted Average
Valuation techniques and inputs
Loans	6,266,972		6,266,972		30,328,429
Recovery analysis \| Recovery rate \| Level 3 \| Minimum
Valuation techniques and inputs
Loans	0.3110		0.3110		0.3510
Recovery analysis \| Recovery rate \| Level 3 \| Maximum
Valuation techniques and inputs
Loans	0.6860		0.6860		0.8520
Recovery analysis \| Recovery rate \| Level 3 \| Weighted Average
Valuation techniques and inputs
Loans	0.5262		0.5262		0.6055
Recovery analysis \| Discount to price \| Level 3 \| Minimum
Valuation techniques and inputs
Loans	0.5440		0.5440
Recovery analysis \| Discount to price \| Level 3 \| Maximum
Valuation techniques and inputs
Loans	0.6250		0.6250
Recovery analysis \| Discount to price \| Level 3 \| Weighted Average
Valuation techniques and inputs
Loans	0.5587		0.5587
Comparable analysis \| Revenue multiple \| Level 3 \| Minimum
Valuation techniques and inputs
Non-marketable equities \| decimal					2.07
Comparable analysis \| Revenue multiple \| Level 3 \| Maximum
Valuation techniques and inputs
Non-marketable equities \| decimal					27.20
Comparable analysis \| Revenue multiple \| Level 3 \| Weighted Average
Valuation techniques and inputs
Non-marketable equities \| decimal					15.51
Comparable analysis \| Level 3
Valuation techniques and inputs
Non-marketable equities	$ 66,000,000		$ 66,000,000		$ 96,000,000
Comparable analysis \| Revenue multiple \| Level 3 \| Minimum
Valuation techniques and inputs
Non-marketable equities	1.3		1.3
Comparable analysis \| Revenue multiple \| Level 3 \| Maximum
Valuation techniques and inputs
Non-marketable equities	19.7		19.7
Comparable analysis \| Revenue multiple \| Level 3 \| Weighted Average
Valuation techniques and inputs
Non-marketable equities	11.07		11.07
Comparable analysis \| Illiquidity discount \| Level 3 \| Minimum
Valuation techniques and inputs
Non-marketable equities	0.1000		0.1000
Comparable analysis \| Illiquidity discount \| Level 3 \| Maximum
Valuation techniques and inputs
Non-marketable equities	0.2210		0.2210
Comparable analysis \| Illiquidity discount \| Level 3 \| Weighted Average
Valuation techniques and inputs
Non-marketable equities	0.1421		0.1421
Loans held-for-sale
Nonrecurring fair value changes included in earnings
Nonrecurring fair value measurements included in earnings	$ (76,000,000)	(38,000,000)	$ (110,000,000)	(51,000,000)
Other real estate owned
Nonrecurring fair value changes included in earnings
Nonrecurring fair value measurements included in earnings	0	0	0	0
Loans
Nonrecurring fair value changes included in earnings
Nonrecurring fair value measurements included in earnings	(9,000,000)	21,000,000	(16,000,000)	3,000,000
Non-marketable equity securities
Nonrecurring fair value changes included in earnings
Nonrecurring fair value measurements included in earnings	$ (8,000,000)	$ 1,000,000	$ 7,000,000	$ (43,000,000)