INVESTMENTS - Schedule of Investment Securities' Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	$ 3,636,537	$ 3,510,536
Available-for-sale debt securities, Less than 12 months, Unrealized loss	380,225	56,088
Available-for-sale debt securities, 12 months or longer, Fair value	752,942	550,108
Available-for-sale debt securities, 12 months or longer, Unrealized loss	141,374	23,109
Available-for-sale debt securities, Total, Fair value	4,389,479	4,060,644
Available-for-sale debt securities, Total, Unrealized loss	521,599	79,197
FNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	751,546
Available-for-sale debt securities, Less than 12 months, Unrealized loss	122,546
Available-for-sale debt securities, 12 months or longer, Fair value	179,874
Available-for-sale debt securities, 12 months or longer, Unrealized loss	35,044
Available-for-sale debt securities, Total, Fair value	931,420
Available-for-sale debt securities, Total, Unrealized loss	157,590
CMO
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	375,687	411,347
Available-for-sale debt securities, Less than 12 months, Unrealized loss	32,423	12,730
Available-for-sale debt securities, 12 months or longer, Fair value	167,328	35,638
Available-for-sale debt securities, 12 months or longer, Unrealized loss	34,565	1,903
Available-for-sale debt securities, Total, Fair value	543,015	446,985
Available-for-sale debt securities, Total, Unrealized loss	66,988	14,633
FNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	3,083,263	3,018,606
Available-for-sale debt securities, Less than 12 months, Unrealized loss	334,083	41,021
Available-for-sale debt securities, 12 months or longer, Fair value	421,083	356,665
Available-for-sale debt securities, 12 months or longer, Unrealized loss	72,326	12,772
Available-for-sale debt securities, Total, Fair value	3,504,346	3,375,271
Available-for-sale debt securities, Total, Unrealized loss	406,409	53,793
FHLMC MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	104,590	11,227
Available-for-sale debt securities, Less than 12 months, Unrealized loss	5,638	348
Available-for-sale debt securities, 12 months or longer, Fair value	8,718	1,917
Available-for-sale debt securities, 12 months or longer, Unrealized loss	1,747	168
Available-for-sale debt securities, Total, Fair value	113,308	13,144
Available-for-sale debt securities, Total, Unrealized loss	7,385	516
GNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	36,513	4,847
Available-for-sale debt securities, Less than 12 months, Unrealized loss	1,626	71
Available-for-sale debt securities, 12 months or longer, Fair value	1,880	0
Available-for-sale debt securities, 12 months or longer, Unrealized loss	312	0
Available-for-sale debt securities, Total, Fair value	38,393	4,847
Available-for-sale debt securities, Total, Unrealized loss	1,938	71
GSE agency notes
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair value	36,484	64,509
Available-for-sale debt securities, Less than 12 months, Unrealized loss	6,455	1,918
Available-for-sale debt securities, 12 months or longer, Fair value	153,933	155,888
Available-for-sale debt securities, 12 months or longer, Unrealized loss	32,424	8,266
Available-for-sale debt securities, Total, Fair value	190,417	220,397
Available-for-sale debt securities, Total, Unrealized loss	$ 38,879	$ 10,184

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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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Amount of accumulated unrealized loss on 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 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on 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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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