MORTGAGE BANKING AND OTHER SERVICED LOANS - Economic Assumptions Used to Estimate Value of MSRs (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Fair value	$ 1,430	$ 1,491
Weighted average life (years)	8 years	8 years 8 months 12 days
Weighted average constant prepayment rate	7.10%	6.70%
Weighted average option adjusted spread	6.08%	6.32%
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	$ 39	$ 35
Decline in fair value from 10% adverse change	$ 40	42
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	$ 72	67
Decline in fair value from 20% adverse change	$ 80	$ 84