Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Due in one year or less	$ 147,306
Due after one year through five years	482,118
Due after five years through ten years	31,209
Due after ten years	680
Mortgage-backed securities	372,458
Total debt securities available-for-sale	1,033,771	$ 1,004,192
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Due in one year or less	147,629
Due after one year through five years	485,745
Due after five years through ten years	31,173
Due after ten years	647
Mortgage-backed securities	375,389
Total debt securities available-for-sale	1,040,583	990,129
U.S. Treasury and Federal agencies securities
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Total debt securities available-for-sale	524,896	537,913
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Total debt securities available-for-sale	526,964	531,223
U.S. States and political subdivisions securities
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Total debt securities available-for-sale	83,566	95,346
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Total debt securities available-for-sale	84,505	94,582
Mortgage-backed securities - Federal agencies
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Total debt securities available-for-sale	372,458	324,390
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Total debt securities available-for-sale	375,389	318,233
Corporate debt securities
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Total debt securities available-for-sale	52,151	45,843
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Total debt securities available-for-sale	53,025	45,392
Foreign government and other securities
Contractual maturities of investments in debt securities available-for-sale, Amortized Cost
Total debt securities available-for-sale	700	700
Contractual maturities of investments in debt securities available-for-sale, Fair Value
Total debt securities available-for-sale	$ 700	$ 699

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
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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