Securities - Gross Unrealized Losses and Fair Value of Company's Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	$ 2,410,434	$ 1,500,686
Unrealized losses less than 12 months	(363,840)	(21,993)
Fair value more than 12 months	268,035	35,281
Unrealized losses more than 12 months	(57,592)	(1,012)
Total fair value	2,678,469	1,535,967
Total unrealized losses	(421,432)	(23,005)
U.S. Treasury and federal agencies
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	478,535	268,732
Unrealized losses less than 12 months	(45,494)	(2,483)
Fair value more than 12 months	57,639	15,820
Unrealized losses more than 12 months	(8,261)	(430)
Total fair value	536,174	284,552
Total unrealized losses	(53,755)	(2,913)
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	1,122,880	539,882
Unrealized losses less than 12 months	(212,110)	(9,389)
Fair value more than 12 months	153,945	19,461
Unrealized losses more than 12 months	(41,323)	(582)
Total fair value	1,276,825	559,343
Total unrealized losses	(253,433)	(9,971)
Federal agency collateralized mortgage obligations
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	93,150	56,027
Unrealized losses less than 12 months	(7,203)	(1,032)
Fair value more than 12 months	0	0
Unrealized losses more than 12 months	0	0
Total fair value	93,150	56,027
Total unrealized losses	(7,203)	(1,032)
Federal agency mortgage-backed pools
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	483,127	406,540
Unrealized losses less than 12 months	(66,195)	(5,418)
Fair value more than 12 months	39,318	0
Unrealized losses more than 12 months	(5,284)	0
Total fair value	522,445	406,540
Total unrealized losses	(71,479)	(5,418)
Private labeled mortgage-backed pools
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	32,755	40,005
Unrealized losses less than 12 months	(4,346)	(442)
Fair value more than 12 months	0	0
Unrealized losses more than 12 months	0	0
Total fair value	32,755	40,005
Total unrealized losses	(4,346)	(442)
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Fair value less than 12 months	199,987	189,500
Unrealized losses less than 12 months	(28,492)	(3,229)
Fair value more than 12 months	17,133	0
Unrealized losses more than 12 months	(2,724)	0
Total fair value	217,120	189,500
Total unrealized losses	$ (31,216)	$ (3,229)