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ALLOWANCE FOR CREDIT LOSSES FOR LOANS AND FINANCE LEASES - Carrying Amount of Portfolios (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	$ 12,385,508	$ 12,185,483
Allowance for credit losses	254,532	261,843	$ 263,592	$ 267,058	$ 265,567	$ 260,464
Residential Mortgage Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	2,809,666	2,821,726
Allowance for credit losses	$ 46,051	$ 57,397	56,689	60,514	64,403	62,760
Residential Mortgage Loans [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	1.64%	2.03%
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	$ 185,957	$ 214,777
Allowance for credit losses	$ 5,646	$ 5,605	6,186	4,804	3,231	2,308
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	3.04%	2.61%
Commercial Portfolio Segment [Member] \| Mortgage loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	$ 2,423,309	$ 2,317,083
Allowance for credit losses	$ 30,078	$ 32,631	32,661	42,427	36,460	35,064
Commercial Portfolio Segment [Member] \| Mortgage loans [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	1.24%	1.41%
Commercial Portfolio Segment [Member] \| Commercial and Industrial loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	$ 3,254,577	$ 3,174,232
Allowance for credit losses	$ 34,448	$ 33,190	34,490	28,014	31,235	32,906
Commercial Portfolio Segment [Member] \| Commercial and Industrial loans [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	1.06%	1.05%
Consumer Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost of loans	$ 3,711,999	$ 3,657,665
Allowance for credit losses	$ 138,309	$ 133,020	$ 133,566	$ 131,299	$ 130,238	$ 127,426
Consumer Portfolio Segment [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	3.73%	3.64%
Loan Total [Member] \| Allowance for loan and lease losses, numerator [Member] \| Loans Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses to amortized cost	2.06%	2.15%