INVESTMENT SECURITIES - Summary of Available-for-Sale Debt Securities by Stated Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Due in one year or less, amortized cost	$ 54,158
Due after one year through five years, amortized cost	199,897
Due after five years through ten years, amortized cost	81,878
Due after ten years, amortized cost	8,750
Amortized Cost	2,045,324	$ 2,087,881
Due in one year or less, fair value	44,830
Due after one year through five years, fair value	174,971
Due after five years through ten years, fair value	70,755
Due after ten years, fair value	8,876
Fair Value	1,979,832	1,985,438
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	281,612
Amortized Cost	281,612	14,820
Debt securities, available-for-sale, without single maturity date, fair value	281,839
Fair Value	281,839	13,236
Agency-guaranteed residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	439,938
Amortized Cost	439,938	330,637
Debt securities, available-for-sale, without single maturity date, fair value	444,086
Fair Value	444,086	327,038
Agency-guaranteed residential collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	488,233
Amortized Cost	488,233	242,858
Debt securities, available-for-sale, without single maturity date, fair value	482,614
Fair Value	482,614	226,746
Agency-guaranteed commercial collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	96,660
Amortized Cost	96,660	95,850
Debt securities, available-for-sale, without single maturity date, fair value	94,789
Fair Value	94,789	93,075
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	10,809
Amortized Cost	10,809	257,500
Debt securities, available-for-sale, without single maturity date, fair value	10,660
Fair Value	10,660	255,407
Private label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, without single maturity date, amortized cost	383,389
Amortized Cost	383,389	502,985
Debt securities, available-for-sale, without single maturity date, fair value	366,412
Fair Value	$ 366,412	$ 475,898

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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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 second through fifth 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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