MORTGAGE BANKING AND OTHER SERVICED LOANS - Economic Assumptions Used to Estimate Value of MSRs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Fair value	$ 1,462	$ 1,455
Weighted average life (years)	8 years 1 month 6 days	8 years
Weighted average constant prepayment rate	6.90%	7.00%
Weighted average option adjusted spread	5.74%	5.88%
Minimum
Servicing Assets at Fair Value [Line Items]
Sensitivity analysis, basis spread	10.00%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Decline in fair value from 10% adverse change	$ 38	$ 38
Decline in fair value from 10% adverse change	$ 39	40
Maximum
Servicing Assets at Fair Value [Line Items]
Sensitivity analysis, basis spread	20.00%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Decline in fair value from 20% adverse change	$ 73	73
Decline in fair value from 20% adverse change	$ 77	$ 80