Securities - Gross Unrealized Losses and Fair Value of Company's Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	$ 1,641,353	$ 1,500,686
Unrealized losses less than 12 months	(290,323)	(21,993)
Fair value more than 12 months	976,521	35,281
Unrealized losses more than 12 months	(262,655)	(1,012)
Total fair value	2,617,874	1,535,967
Total unrealized losses	(552,978)	(23,005)
U.S. Treasury and federal agencies
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	326,455	268,732
Unrealized losses less than 12 months	(34,174)	(2,483)
Fair value more than 12 months	187,559	15,820
Unrealized losses more than 12 months	(40,901)	(430)
Total fair value	514,014	284,552
Total unrealized losses	(75,075)	(2,913)
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	924,192	539,882
Unrealized losses less than 12 months	(198,105)	(9,389)
Fair value more than 12 months	369,729	19,461
Unrealized losses more than 12 months	(134,765)	(582)
Total fair value	1,293,921	559,343
Total unrealized losses	(332,870)	(9,971)
Federal agency collateralized mortgage obligations
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	47,014	56,027
Unrealized losses less than 12 months	(2,897)	(1,032)
Fair value more than 12 months	37,291	0
Unrealized losses more than 12 months	(7,040)	0
Total fair value	84,305	56,027
Total unrealized losses	(9,937)	(1,032)
Federal agency mortgage-backed pools
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	275,203	406,540
Unrealized losses less than 12 months	(42,992)	(5,418)
Fair value more than 12 months	211,935	0
Unrealized losses more than 12 months	(46,511)	0
Total fair value	487,138	406,540
Total unrealized losses	(89,503)	(5,418)
Private labeled mortgage-backed pools
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	4,398	40,005
Unrealized losses less than 12 months	(730)	(442)
Fair value more than 12 months	26,369	0
Unrealized losses more than 12 months	(4,674)	0
Total fair value	30,767	40,005
Total unrealized losses	(5,404)	(442)
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	64,091	189,500
Unrealized losses less than 12 months	(11,425)	(3,229)
Fair value more than 12 months	143,638	0
Unrealized losses more than 12 months	(28,764)	0
Total fair value	207,729	189,500
Total unrealized losses	$ (40,189)	$ (3,229)