Securities, Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Available-for-sale [Abstract]
Amortized cost	$ 1,346,551	$ 978,774
Gross unrealized gains	16,253	19,273
Gross unrealized losses	(5,207)	(786)
Fair value	1,357,597	997,261
U.S. Treasury and Government Agencies [Member]
Available-for-sale [Abstract]
Amortized cost	245,706	148,507
Gross unrealized gains	920	483
Gross unrealized losses	(931)	(197)
Fair value	245,695	148,793
State and Political Subdivisions [Member]
Available-for-sale [Abstract]
Amortized cost	257,011	133,287
Gross unrealized gains	6,733	7,132
Gross unrealized losses	(2,167)	(3)
Fair value	261,577	140,416
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale [Abstract]
Amortized cost	751,580	640,537
Gross unrealized gains	8,198	11,648
Gross unrealized losses	(2,028)	(378)
Fair value	757,750	651,807
Other Debt Securities [Member]
Available-for-sale [Abstract]
Amortized cost	92,254	56,443
Gross unrealized gains	402	10
Gross unrealized losses	(81)	(208)
Fair value	$ 92,575	$ 56,245

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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Amount 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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