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	159,909		159,909
Other comprehensive income (loss)	(109,478)			(109,478)
Issuance of common stock - employee stock purchase plan, shares		74
Issuance of common stock - employee stock purchase plan, value	$ 2,351	$ 2,351
Activity in Deferred Compensation Plan, shares	0
Activity in Deferred Compensation Plan, value	$ (8)
Issuance of common stock - RSAs and RSUs, net of canceled awards, shares		178
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	10,835	$ 10,835
Purchase and retirement of common stock, shares		(90)
Purchase and retirement of common stock, value	(4,100)	$ (4,100)
Cash dividends declared on common stock	(83,849)		(83,849)
Balance, value at Sep. 30, 2021	2,323,267	$ 1,670,076	651,308	72,717	(70,834)
Shares, Outstanding		71,742
Balance, value at Jun. 30, 2021	2,333,246	$ 1,664,953	642,018	97,109	(70,834)
Net income	53,017		53,017
Other comprehensive income (loss)	(24,392)			(24,392)
Issuance of common stock - employee stock purchase plan, shares		33
Issuance of common stock - employee stock purchase plan, value	1,253	$ 1,253
Issuance of common stock - RSAs and RSUs, net of canceled awards, shares		(14)
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	3,899	$ 3,899
Purchase and retirement of common stock, shares		(1)
Purchase and retirement of common stock, value	(29)	$ (29)
Cash dividends declared on common stock	(43,727)		(43,727)
Balance, value at Sep. 30, 2021	2,323,267	$ 1,670,076	651,308	72,717	(70,834)
Shares, Outstanding		71,760
Shares, Outstanding		78,511
Balance, value at Dec. 31, 2021	2,588,742	$ 1,930,187	694,227	35,162	(70,834)
Net income	181,272		181,272
Other comprehensive income (loss)	(594,006)			(594,006)
Issuance of common stock - employee stock purchase plan, shares		68
Issuance of common stock - employee stock purchase plan, value	2,110	$ 2,110
Activity in Deferred Compensation Plan, shares		0
Activity in Deferred Compensation Plan, value	4	$ 4
Issuance of common stock - RSAs and RSUs, net of canceled awards, shares		177
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	12,059	$ 12,059
Purchase and retirement of common stock, shares		(109)
Purchase and retirement of common stock, value	(3,975)	$ (3,975)
Cash dividends declared on common stock	(70,725)		(70,725)
Balance, value at Sep. 30, 2022	2,115,481	$ 1,940,385	804,774	(558,844)	(70,834)
Shares, Outstanding		78,621
Balance, value at Jun. 30, 2022	2,243,218	$ 1,935,180	763,487	(384,615)	(70,834)
Net income	64,942		64,942
Other comprehensive income (loss)	(174,229)			(174,229)
Issuance of common stock - employee stock purchase plan, shares		37
Issuance of common stock - employee stock purchase plan, value	1,093	$ 1,093
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		(10)
Issuance of common stock - RSAs and RSUs, net of canceled awards, value	4,149	$ 4,149
Purchase and retirement of common stock, shares		1
Purchase and retirement of common stock, value	(38)	$ (38)
Cash dividends declared on common stock	(23,655)		(23,655)
Balance, value at Sep. 30, 2022	$ 2,115,481	$ 1,940,385	$ 804,774	$ (558,844)	$ (70,834)
Shares, Outstanding		78,647