Investment Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 1,187,499	$ 1,028,883
Gross Unrealized/Unrecognized Holding Gains	28,425	453
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6,223	25,915
Debt Securities, Available-for-sale	1,209,701	1,003,421
Debt Securities, Held-to-maturity	0	351,808
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain		3,289
Gross Unrealized/Unrecognized Holding Losses		3,675
Debt Securities, Held-to-maturity, Fair Value		351,422
Obligations of States and Political Subdivisions
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	302,928
Gross Unrealized/Unrecognized Holding Gains	17,563
Debt Securities, Available-for-sale	320,491
Debt Securities, Held-to-maturity		305,278
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain		3,202
Gross Unrealized/Unrecognized Holding Losses		2,672
Debt Securities, Held-to-maturity, Fair Value		305,808
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	884,571	1,028,883
Gross Unrealized/Unrecognized Holding Gains	10,862	453
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6,223	25,915
Debt Securities, Available-for-sale	$ 889,210	1,003,421
Debt Securities, Held-to-maturity		46,530
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain		87
Gross Unrealized/Unrecognized Holding Losses		1,003
Debt Securities, Held-to-maturity, Fair Value		$ 45,614

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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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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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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