Securities, Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Available for sale, amortized cost [Abstract]
Due in one year or less	$ 77,420
Due after one through five years	18,480
Due after five through ten years	96,870
Due after ten years	89,024
Amortized cost	978,774	$ 593,945
Available for sale, fair value [Abstract]
Due in one year or less	77,424
Due after one through five years	19,005
Due after five through ten years	98,417
Due after ten years	94,363
Fair value	997,261	599,844
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available for sale, amortized cost [Abstract]
Without single maturity date	640,537
Amortized cost	640,537	291,874
Available for sale, fair value [Abstract]
Without single maturity date	651,807
Fair value	651,807	295,245
Other Debt Obligations [Member]
Available for sale, amortized cost [Abstract]
Without single maturity date	56,443
Amortized cost	56,443	31,418
Available for sale, fair value [Abstract]
Without single maturity date	56,245
Fair value	$ 56,245	$ 31,142

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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