BORROWINGS - Narrative (Detail) - USD ($)			3 Months Ended
	Mar. 15, 2022	Nov. 05, 2019	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Subordinated debentures [Line Items]:
Subordinated debt				$ 371,400,000	$ 370,803,000
Percentage of principal and accrued interest of retail repurchase agreements collateralized				102.50%
FHLB availability				$ 3,200,000,000	3,100,000,000
FHLB advances outstanding				250,000,000.0	550,000,000
Unsecured Lines Of Credit, Correspondent Banks
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				903,000,000.0	1,200,000,000
Federal Reserve Bank Term Funding Program
Subordinated debentures [Line Items]:
Repayments of debt			$ 300,000,000
Federal Reserve and Correspondent Banks
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				772,300,000	651,300,000
Long-term line of credit				0	0
Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				3,400,000,000	3,600,000,000
Residential Mortgage | Asset Pledged as Collateral | Federal Home Loan Bank Advances | Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				1,400,000,000	1,400,000,000
Commercial real estate loans | Asset Pledged as Collateral | Federal Home Loan Bank Advances | Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				3,900,000,000	4,000,000,000.0
HELOC | Asset Pledged as Collateral | Federal Home Loan Bank Advances | Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				228,700,000	209,200,000
Multifamily Loans | Asset Pledged as Collateral | Federal Home Loan Bank Advances | Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing				559,300,000	$ 538,600,000
Fixed Floating Rate Subordinated Notes Due 2029
Subordinated debentures [Line Items]:
Subordinated debt, gross				$ 140,000,000
Federal funds purchased
Subordinated debentures [Line Items]:
Interest rate				0.00%	0.00%
Other short-term borrowings				$ 0	$ 0
Subordinated Debt
Subordinated debentures [Line Items]:
Subordinated debt, gross				$ 375,000,000	375,000,000
Subordinated Debt | Fixed Floating Rate Subordinated Notes Due 2032
Subordinated debentures [Line Items]:
Subordinated debt	$ 200,000,000
Interest rate	3.875%			3.875%
Basis spread on variable rate	1.965%
Unamortized discount (premium) and debt issuance costs, net	$ 3,100,000
Subordinated debt, gross				$ 200,000,000	200,000,000
Subordinated Debt | Fixed Floating Rate Subordinated Notes Due 2029
Subordinated debentures [Line Items]:
Subordinated debt		$ 175,000,000.0
Interest rate		4.25%
Basis spread on variable rate		2.88%
Effective rate				7.41%
Unamortized discount (premium) and debt issuance costs, net		$ 2,900,000
Subordinated debt, gross				$ 175,000,000	$ 175,000,000
Subordinated Debt | Fixed Floating Rate Subordinated Notes Due 2029 | Maximum
Subordinated debentures [Line Items]:
Term of debt				5 years
Subordinated Debt | Fixed Floating Rate Subordinated Notes Due 2029 | Minimum
Subordinated debentures [Line Items]:
Term of debt				4 years
Subordinated Debt | Fixed Floating Rate Subordinated Notes Due 2029 | Benchmark Adjustment
Subordinated debentures [Line Items]:
Basis spread on variable rate		0.26%