INVESTMENT SECURITIES - Schedule of Investment Securities' Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	$ 5,022	$ 19,611
Available-for-sale debt securities, Less than 12 months, Unrealized loss	10	342
Available-for-sale debt securities, 12 months or longer, Fair value	3,669,681	3,819,041
Available-for-sale debt securities, 12 months or longer, Unrealized loss	555,094	657,631
Available-for-sale debt securities, Total, Fair value	3,674,703	3,838,652
Available-for-sale debt securities, Total, Unrealized loss	555,104	657,973
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	444,751	464,619
Available-for-sale debt securities, 12 months or longer, Unrealized loss	82,749	96,333
Available-for-sale debt securities, Total, Fair value	444,751	464,619
Available-for-sale debt securities, Total, Unrealized loss	82,749	96,333
FNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	3,126	9,068
Available-for-sale debt securities, Less than 12 months, Unrealized loss	7	125
Available-for-sale debt securities, 12 months or longer, Fair value	2,889,219	3,026,520
Available-for-sale debt securities, 12 months or longer, Unrealized loss	423,825	502,449
Available-for-sale debt securities, Total, Fair value	2,892,345	3,035,588
Available-for-sale debt securities, Total, Unrealized loss	423,832	502,574
FHLMC MBS
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	111,801	115,525
Available-for-sale debt securities, 12 months or longer, Unrealized loss	8,763	11,324
Available-for-sale debt securities, Total, Fair value	111,801	115,525
Available-for-sale debt securities, Total, Unrealized loss	8,763	11,324
GNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	1,896	10,543
Available-for-sale debt securities, Less than 12 months, Unrealized loss	3	217
Available-for-sale debt securities, 12 months or longer, Fair value	37,791	31,681
Available-for-sale debt securities, 12 months or longer, Unrealized loss	2,365	2,782
Available-for-sale debt securities, Total, Fair value	39,687	42,224
Available-for-sale debt securities, Total, Unrealized loss	2,368	2,999
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	186,119	180,696
Available-for-sale debt securities, 12 months or longer, Unrealized loss	37,392	44,743
Available-for-sale debt securities, Total, Fair value	186,119	180,696
Available-for-sale debt securities, Total, Unrealized loss	$ 37,392	$ 44,743

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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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