Investment Securities - Schedule of Investment Securities' Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	$ 3,510,536	$ 579,528
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	56,088	2,076
Available-for-sale debt securities, 12 months or longer, Fair Value	550,108	4,355
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	23,109	3
Available-for-sale debt securities, Total, Fair Value	4,060,644	583,883
Available-for-sale debt securities, Total, Unrealized Loss	79,197	2,079
CMO
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	411,347	183,983
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	12,730	443
Available-for-sale debt securities, 12 months or longer, Fair Value	35,638	0
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	1,903	0
Available-for-sale debt securities, Total, Fair Value	446,985	183,983
Available-for-sale debt securities, Total, Unrealized Loss	14,633	443
FNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	3,018,606	289,338
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	41,021	879
Available-for-sale debt securities, 12 months or longer, Fair Value	356,665	4,355
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	12,772	3
Available-for-sale debt securities, Total, Fair Value	3,375,271	293,693
Available-for-sale debt securities, Total, Unrealized Loss	53,793	882
FHLMC MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	11,227	5,191
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	348	105
Available-for-sale debt securities, 12 months or longer, Fair Value	1,917	0
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	168	0
Available-for-sale debt securities, Total, Fair Value	13,144	5,191
Available-for-sale debt securities, Total, Unrealized Loss	516	105
GNMA MBS
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	4,847
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	71
Available-for-sale debt securities, 12 months or longer, Fair Value	0
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	0
Available-for-sale debt securities, Total, Fair Value	4,847
Available-for-sale debt securities, Total, Unrealized Loss	71
GSE agency notes
Available-for-sale debt securities:
Available-for-sale debt securities, Less than 12 months, Fair Value	64,509	101,016
Available-for-sale debt securities, Less than 12 months, Unrealized Loss	1,918	649
Available-for-sale debt securities, 12 months or longer, Fair Value	155,888	0
Available-for-sale debt securities, 12 months or longer, Unrealized Loss	8,266	0
Available-for-sale debt securities, Total, Fair Value	220,397	101,016
Available-for-sale debt securities, Total, Unrealized Loss	$ 10,184	$ 649

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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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