Debt Securities - Investments Classified by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Due in one year or less, amortized cost	$ 42,982
Due after one year through five years, amortized cost	185,876
Due after five years through ten years, amortized cost	225,762
Due after ten years, amortized cost	74,562
Total maturing securities, amortized cost	529,182
Amortized Cost	871,660	$ 780,061
Fair Value
Due in one year or less, estimated fair value	43,030
Due after one year through five years, estimated fair value	186,530
Due after five years through ten years, estimated fair value	227,898
Due after ten years, estimated fair value	74,940
Total maturing securities, fair value	532,398
Debt securities available for sale at fair value	881,859	785,977
Mortgage-backed securities
Amortized Cost
Amortized Cost	41,191	43,009
Fair Value
Debt securities available for sale at fair value	42,601	43,530
Collateralized mortgage obligations
Amortized Cost
Amortized Cost	301,287	293,911
Fair Value
Debt securities available for sale at fair value	$ 306,860	$ 292,946

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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