Investments - Revenue and General Obligation Bonds by Location (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 1,145,141
Investment securities available for sale	1,069,434
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	363,790
Investment securities available for sale	320,729
Amortized cost (available-for-sale securities and held-to-maturity securities)	413,114
Fair market value (available-for-sale securities and held-to-maturity securities)	363,118
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)	356,902
Fair market value (available-for-sale securities and held-to-maturity securities)	313,684
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)	159,391
Fair market value (available-for-sale securities and held-to-maturity securities)	139,498
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)	67,310
Fair market value (available-for-sale securities and held-to-maturity securities)	58,161
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)	22,417
Fair market value (available-for-sale securities and held-to-maturity securities)	20,670
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)	107,784
Fair market value (available-for-sale securities and held-to-maturity securities)	95,355
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)	56,212
Fair market value (available-for-sale securities and held-to-maturity securities)	49,434
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)	9,496
Fair market value (available-for-sale securities and held-to-maturity securities)	8,460
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)	3,994
Fair market value (available-for-sale securities and held-to-maturity securities)	3,613
Amortized Cost (before ASU 2016-13)		1,349
Investment securities available for sale (before ASU 2016-13)		1,392
Revenue Bonds [Member] \| WASHINGTON
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	4,093
Fair market value (available-for-sale securities and held-to-maturity securities)	3,387
Amortized Cost (before ASU 2016-13)		4,334
Investment securities available for sale (before ASU 2016-13)		4,602
Revenue Bonds [Member] \| Other [Member]
Marketable Securities [Line Items]
Amortized cost (available-for-sale securities and held-to-maturity securities)	38,629
Fair market value (available-for-sale securities and held-to-maturity securities)	$ 33,974
Amortized Cost (before ASU 2016-13)		29,976
Investment securities available for sale (before ASU 2016-13)		$ 31,215

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