INVESTMENT SECURITIES - Summary of Available-for-Sale Debt Securities by Stated Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Due in one year or less, amortized cost	$ 73,585
Due after one year through five years, amortized cost	115,513
Due after five years through ten years, amortized cost	105,131
Amortized Cost	2,028,458	$ 1,982,147
Due in one year or less, fair value	61,427
Due after one year through five years, fair value	92,456
Due after five years through ten years, fair value	92,415
Fair Value	1,961,852	1,906,535
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	273,593
Amortized Cost	273,593	239,259
Debt securities, available-for-sale, without single maturity date, fair value	275,706
Fair Value	275,706	237,813
Agency-guaranteed residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	491,169
Amortized Cost	491,169	410,648
Debt securities, available-for-sale, without single maturity date, fair value	490,860
Fair Value	490,860	413,761
Agency-guaranteed residential collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	481,331
Amortized Cost	481,331	496,595
Debt securities, available-for-sale, without single maturity date, fair value	476,658
Fair Value	476,658	493,507
Agency-guaranteed commercial collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	117,586
Amortized Cost	117,586	118,049
Debt securities, available-for-sale, without single maturity date, fair value	113,424
Fair Value	113,424	115,576
Private label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	370,550
Amortized Cost	370,550	376,803
Debt securities, available-for-sale, without single maturity date, fair value	358,906
Fair Value	$ 358,906	$ 360,020

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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