Investments - Revenue Bonds by Type (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 924,538
Investment securities available for sale	864,178
Amortized Cost (before ASU 2016-13)		$ 957,459
Investment securities available for sale (before ASU 2016-13)		973,314
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Amortized Cost	286,650
Investment securities available for sale	254,888
Amortized cost (available-for-sale securities and held-to-maturity securities)	337,417
Fair market value (available-for-sale securities and held-to-maturity securities)	299,737
Amortized Cost (before ASU 2016-13)		290,729
Investment securities available for sale (before ASU 2016-13)		304,268
Revenue Bonds [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	45,886
Fair market value (available-for-sale securities and held-to-maturity securities)	40,781
Amortized Cost (before ASU 2016-13)		42,697
Investment securities available for sale (before ASU 2016-13)		44,586
Revenue Bonds [Member] \| Water [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	17,120
Fair market value (available-for-sale securities and held-to-maturity securities)	15,112
Amortized Cost (before ASU 2016-13)		15,534
Investment securities available for sale (before ASU 2016-13)		16,220
Revenue Bonds [Member] \| Sewer [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	6,107
Fair market value (available-for-sale securities and held-to-maturity securities)	5,356
Amortized Cost (before ASU 2016-13)		3,932
Investment securities available for sale (before ASU 2016-13)		4,165
Revenue Bonds [Member] \| Lease [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	4,665
Fair market value (available-for-sale securities and held-to-maturity securities)	4,341
Amortized Cost (before ASU 2016-13)		6,556
Investment securities available for sale (before ASU 2016-13)		6,718
Revenue Bonds [Member] \| Sales Tax [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	3,559
Fair market value (available-for-sale securities and held-to-maturity securities)	3,067
Revenue Bonds [Member] \| Intergovernmental Agreement [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	2,838
Fair market value (available-for-sale securities and held-to-maturity securities)	2,680
Revenue Bonds [Member] \| Other Revenue Source [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	11,597
Fair market value (available-for-sale securities and held-to-maturity securities)	$ 10,225
Amortized Cost (before ASU 2016-13)		16,675
Investment securities available for sale (before ASU 2016-13)		$ 17,483

Debt Securities, Excluding Accrued Interest, Amortized Cost

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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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