Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income
Adjustment to opening retained earnings, net of tax, pursuant to adoption of ASU | Accounting Standards Update 2016-01	$ 782			$ 782	$ 0
Balance, value at Dec. 31, 2018	2,033,649	$ 1,642,246	$ 0	426,708	(35,305)
Balance (in shares) at Dec. 31, 2018		73,249
Net income	194,451			194,451
Other comprehensive income	75,672				75,672
Issuance of common stock - stock option and other plans, shares		59
Issuance of common stock - stock option and other plans, value	2,025	$ 2,025
Issuance of common stock - restricted stock awards, net of canceled awards, shares		343
Issuance of common stock - restricted stock awards, net of canceled awards, value	9,271	$ 9,271
Activity in deferred compensation	3
Purchase and retirement of common stock, shares		(74)
Purchase and retirement of common stock, value	(2,792)	$ (2,792)
Cash dividends declared on common stock	(102,265)			(102,265)
Purchase of treasury stock, shares		1,453
Purchase of treasury stock, value	(50,834)		(50,834)
Balance, value at Dec. 31, 2019	$ 2,159,962	$ 1,650,753	(50,834)	519,676	40,367
Balance (in shares) at Dec. 31, 2019		72,124
Common Stock, Dividends, Per Share, paid	$ 1.40
Adjustment to opening retained earnings, net of tax, pursuant to adoption of ASU | Accounting Standards Update 2016-02	$ (2,457)			(2,457)
Net income	154,244			154,244
Other comprehensive income	141,828				141,828
Issuance of common stock - stock option and other plans, shares		65
Issuance of common stock - stock option and other plans, value	2,028	$ 2,028
Issuance of common stock - restricted stock awards, net of canceled awards, shares		208
Issuance of common stock - restricted stock awards, net of canceled awards, value	10,737	$ 10,737
Activity in deferred compensation	2	$ 2
Purchase and retirement of common stock, shares		(68)
Purchase and retirement of common stock, value	(2,522)	$ (2,522)
Cash dividends declared on common stock	(96,215)			(96,215)
Purchase of treasury stock, shares		731
Purchase of treasury stock, value	(20,000)		(20,000)
Balance, value at Dec. 31, 2020	$ 2,347,607	$ 1,660,998	(70,834)	575,248	182,195
Balance (in shares) at Dec. 31, 2020		71,598
Common Stock, Dividends, Per Share, paid	$ 1.34
Net income	$ 202,820			202,820
Other comprehensive income	$ (147,033)				(147,033)
Stock Issued During Period, Shares, Acquisitions	6,740
Stock Issued During Period, Value, Acquisitions	$ 256,061	$ 256,061
Issuance of common stock - stock option and other plans, shares		74
Issuance of common stock - stock option and other plans, value	2,350	$ 2,350
Issuance of common stock - restricted stock awards, net of canceled awards, shares		190
Issuance of common stock - restricted stock awards, net of canceled awards, value	14,926	$ 14,926
Activity in deferred compensation	(8)	$ (8)
Purchase and retirement of common stock, shares		(91)
Purchase and retirement of common stock, value	(4,140)	$ (4,140)
Cash dividends declared on common stock	(83,841)			(83,841)
Balance, value at Dec. 31, 2021	$ 2,588,742	$ 1,930,187	$ (70,834)	$ 694,227	$ 35,162
Balance (in shares) at Dec. 31, 2021		78,511
Common Stock, Dividends, Per Share, paid	$ 1.14