Investment Securities - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Available for Sale Securities, Amortized Cost
Within one year	$ 321,992	$ 118,984
After one through five years	86,743	203,236
Total, single maturity date	408,735	322,220
Total	657,232	337,387
Available for Sale Securities, Fair Value
Within one year	316,487	115,386
After one through five years	83,020	192,784
Total, single maturity date	399,507	308,170
Total	648,003	323,337
Held to Maturity Securities, Amortized Cost
Total	1,062,017	1,119,078
Held to Maturity Securities, Fair Value
Total	1,058,590	1,118,966
Held to maturity securities:
Amortized Cost	1,062,017	1,119,078
Fair Value	1,058,590	1,118,966
Mortgage-backed - Government-sponsored entity (GSE)
Available for Sale Securities, Amortized Cost
Without single maturity date	248,497	15,167
Total	248,497	15,167
Available for Sale Securities, Fair Value
Without single maturity date	248,496	15,167
Total	248,496	15,167
Held to Maturity Securities, Amortized Cost
Total	4,249	247,306
Held to Maturity Securities, Fair Value
Total	3,939	247,182
Held to maturity securities:
Amortized Cost	4,249	247,306
Fair Value	3,939	247,182
Mortgage-backed - Non-GSE multi-family
Held to Maturity Securities, Amortized Cost
Total	835,649	871,772
Held to Maturity Securities, Fair Value
Total	835,607	871,784
Held to maturity securities:
Amortized Cost	835,649	871,772
Fair Value	835,607	871,784
Mortgage-backed - Non-GSE residential
Held to Maturity Securities, Amortized Cost
Total	222,119	247,306
Held to Maturity Securities, Fair Value
Total	219,044	247,182
Held to maturity securities:
Amortized Cost	222,119	247,306
Fair Value	$ 219,044	$ 247,182