INVESTMENT SECURITIES - Schedule of Investment Securities' Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	$ 40,645	$ 51,381
Available-for-sale debt securities, Less than 12 months, Unrealized loss	283	668
Available-for-sale debt securities, 12 months or longer, Fair value	3,331,456	3,430,940
Available-for-sale debt securities, 12 months or longer, Unrealized loss	529,328	707,235
Available-for-sale debt securities, Total, Fair value	3,372,101	3,482,321
Available-for-sale debt securities, Total, Unrealized loss	529,611	707,903
CMO
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	0	0
Available-for-sale debt securities, Less than 12 months, Unrealized loss	0	0
Available-for-sale debt securities, 12 months or longer, Fair value	406,409	420,663
Available-for-sale debt securities, 12 months or longer, Unrealized loss	74,326	95,967
Available-for-sale debt securities, Total, Fair value	406,409	420,663
Available-for-sale debt securities, Total, Unrealized loss	74,326	95,967
FNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	36,195	46,971
Available-for-sale debt securities, Less than 12 months, Unrealized loss	167	525
Available-for-sale debt securities, 12 months or longer, Fair value	2,598,550	2,691,778
Available-for-sale debt securities, 12 months or longer, Unrealized loss	409,846	549,486
Available-for-sale debt securities, Total, Fair value	2,634,745	2,738,749
Available-for-sale debt securities, Total, Unrealized loss	410,013	550,011
FHLMC MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	0	6
Available-for-sale debt securities, Less than 12 months, Unrealized loss	0	0
Available-for-sale debt securities, 12 months or longer, Fair value	104,548	105,508
Available-for-sale debt securities, 12 months or longer, Unrealized loss	8,357	13,091
Available-for-sale debt securities, Total, Fair value	104,548	105,514
Available-for-sale debt securities, Total, Unrealized loss	8,357	13,091
GNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	4,450	4,404
Available-for-sale debt securities, Less than 12 months, Unrealized loss	116	143
Available-for-sale debt securities, 12 months or longer, Fair value	35,184	35,054
Available-for-sale debt securities, 12 months or longer, Unrealized loss	2,624	3,759
Available-for-sale debt securities, Total, Fair value	39,634	39,458
Available-for-sale debt securities, Total, Unrealized loss	2,740	3,902
GSE agency notes
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	0	0
Available-for-sale debt securities, Less than 12 months, Unrealized loss	0	0
Available-for-sale debt securities, 12 months or longer, Fair value	186,765	177,937
Available-for-sale debt securities, 12 months or longer, Unrealized loss	34,175	44,932
Available-for-sale debt securities, Total, Fair value	186,765	177,937
Available-for-sale debt securities, Total, Unrealized loss	$ 34,175	$ 44,932

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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