Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
Shares, Outstanding		71,598
Balance, value at Dec. 31, 2020	$ 2,347,607	$ 1,660,998	$ 575,248	$ 182,195	$ (70,834)
Net income	51,853		51,853
Other comprehensive income (loss)	(104,467)			(104,467)
Issuance of common stock - employee stock purchase plan, shares		41
Issuance of common stock - employee stock purchase plan, value	1,098	$ 1,098
Issuance of common stock - RSAs and RSUs, net of canceled awards, shares		188
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	3,028	$ 3,028
Purchase and retirement of common stock, shares		(88)
Purchase and retirement of common stock, value	(3,995)	$ (3,995)
Cash dividends declared on common stock	(20,061)		(20,061)
Balance, value at Mar. 31, 2021	2,275,063	$ 1,661,129	607,040	77,728	(70,834)
Shares, Outstanding		71,739
Shares, Outstanding		78,511
Balance, value at Dec. 31, 2021	2,588,742	$ 1,930,187	694,227	35,162	(70,834)
Net income	57,522		57,522
Other comprehensive income (loss)	(262,939)			(262,939)
Issuance of common stock - employee stock purchase plan, shares		31
Issuance of common stock - employee stock purchase plan, value	1,017	$ 1,017
Activity in Deferred Compensation Plan, shares		0
Activity in Deferred Compensation Plan, value	1	$ 1
Issuance of common stock - RSAs and RSUs, net of canceled awards, shares		210
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	3,795	$ 3,795
Purchase and retirement of common stock, shares		108
Purchase and retirement of common stock, value	(3,924)	$ (3,924)
Cash dividends declared on common stock	(23,435)		(23,435)
Balance, value at Mar. 31, 2022	$ 2,360,779	$ 1,931,076	$ 728,314	$ (227,777)	$ (70,834)
Shares, Outstanding		78,644