Investments - Revenue and General Obligation Bonds by Location (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
General Obligation Bonds [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	291,531
Fair market value (available-for-sale securities and held-to-maturity securities)	258,956
Amortized Cost (before ASU 2016-13)		248,032
Investment securities available for sale (before ASU 2016-13)		259,682
General Obligation Bonds [Member] \| TEXAS
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	114,615
Fair market value (available-for-sale securities and held-to-maturity securities)	100,728
Amortized Cost (before ASU 2016-13)		85,045
Investment securities available for sale (before ASU 2016-13)		89,225
General Obligation Bonds [Member] \| CALIFORNIA
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	64,337
Fair market value (available-for-sale securities and held-to-maturity securities)	56,481
Amortized Cost (before ASU 2016-13)		64,092
Investment securities available for sale (before ASU 2016-13)		67,066
General Obligation Bonds [Member] \| WASHINGTON
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	20,724
Fair market value (available-for-sale securities and held-to-maturity securities)	19,476
Amortized Cost (before ASU 2016-13)		23,858
Investment securities available for sale (before ASU 2016-13)		24,812
General Obligation Bonds [Member] \| Other [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	91,855
Fair market value (available-for-sale securities and held-to-maturity securities)	82,271
Amortized Cost (before ASU 2016-13)		75,037
Investment securities available for sale (before ASU 2016-13)		78,579
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] \| TEXAS
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	5,739
Fair market value (available-for-sale securities and held-to-maturity securities)	5,118
Amortized Cost (before ASU 2016-13)		7,038
Investment securities available for sale (before ASU 2016-13)		7,377
Revenue Bonds [Member] \| CALIFORNIA
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	3,997
Fair market value (available-for-sale securities and held-to-maturity securities)	3,616
Amortized Cost (before ASU 2016-13)		4,334
Investment securities available for sale (before ASU 2016-13)		4,602
Revenue Bonds [Member] \| WASHINGTON
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	4,103
Fair market value (available-for-sale securities and held-to-maturity securities)	3,502
Amortized Cost (before ASU 2016-13)		1,349
Investment securities available for sale (before ASU 2016-13)		1,392
Revenue Bonds [Member] \| Other [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	32,047
Fair market value (available-for-sale securities and held-to-maturity securities)	$ 28,545
Amortized Cost (before ASU 2016-13)		29,976
Investment securities available for sale (before ASU 2016-13)		$ 31,215

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