CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative change in accounting principle upon adoption of new accounting pronouncement	Common Stock	Paid-in Capital	Retained Earnings	Retained Earnings Cumulative change in accounting principle upon adoption of new accounting pronouncement	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2018			51,361
Beginning balance at Dec. 31, 2018	$ 864,267		$ 5,136	$ 778,501	$ 97,074		$ (3,384)	$ (13,060)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	116,264				98,739			17,525
Stock based compensation expense (in shares)			30
Stock based compensation expense	7,244			7,244
Common stock issued for stock based employee benefit plans (in shares)			94
Common stock issued for stock based employee benefit plans	(2,668)		$ 12	(32)			(2,648)
Common stock issued for stock options (in shares)			29
Common stock issued for stock options	428		$ 3	425
Other	104			104
Ending balance (in shares) at Dec. 31, 2019			51,514
Ending balance at Dec. 31, 2019	985,639	$ (16,876)	$ 5,151	786,242	195,813	$ (16,876)	(6,032)	4,465
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	93,669				77,764			15,905
Stock based compensation expense (in shares)			39
Stock based compensation expense	7,304			7,304
Common stock issued for stock based employee benefit plans (in shares)			465
Common stock issued for stock based employee benefit plans	(2,252)		$ 51	(50)			(2,253)
Common stock issued for stock options (in shares)			62
Common stock issued for stock options	766		$ 6	760
Issuance of common stock, pursuant to acquisition (in shares)			3,163
Issuance of common stock, pursuant to acquisition	62,152		$ 316	61,836
Ending balance (in shares) at Dec. 31, 2020			55,243
Ending balance at Dec. 31, 2020	1,130,402		$ 5,524	856,092	256,701		(8,285)	20,370
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	97,039				124,403			(27,364)
Stock based compensation expense (in shares)			23
Stock based compensation expense	8,685			8,685
Common stock issued for stock based employee benefit plans (in shares)			167
Common stock issued for stock based employee benefit plans	(2,314)		$ 19	(49)			(2,284)
Common stock issued for stock options (in shares)			384
Common stock issued for stock options	7,336		$ 38	7,298
Issuance of common stock, pursuant to acquisition (in shares)			2,687
Issuance of common stock, pursuant to acquisition	86,487		$ 269	86,218
Conversion of options, pursuant to acquisition	5,607			5,607
Dividends on common stock ($0.39 per share)	(22,506)				(22,506)
Ending balance (in shares) at Dec. 31, 2021			58,504
Ending balance at Dec. 31, 2021	$ 1,310,736		$ 5,850	$ 963,851	$ 358,598		$ (10,569)	$ (6,994)