Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
Beginning Balance at Dec. 31, 2016	$ 2,121,115	$ 549,707	$ 1,467,602	$ 732,099	$ (38,449)	$ (589,844)
Beginning Balance (in shares) at Dec. 31, 2016		174,040
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	171,753			171,753
Other comprehensive income (loss)	5,475				5,475
Stock issued, including related tax benefits	8,538	$ 2,525	5,578			435
Stock issued, including related tax benefits (in shares)		1,130
Stock-based compensation awards	5,209		5,209
Common stock cash dividends	(82,233)			(82,233)
Ending Balance at Dec. 31, 2017	2,229,857	$ 552,232	1,478,389	821,619	(32,974)	(589,409)
Ending Balance (in shares) at Dec. 31, 2017		175,170
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	208,393			208,393
Other comprehensive income (loss)	(18,988)				(18,988)
Stock issued, including related tax benefits	6,735	$ 2,062	3,432			1,241
Stock issued, including related tax benefits (in shares)		977
Stock-based compensation awards (in shares)		33
Stock-based compensation awards	7,965	$ 83	7,882
Acquisition of treasury stock	(95,308)					(95,308)
Reclassification of stranded tax effects	(7,101)			7,101	(7,101)
Acquisition of treasury stock (in shares)		(5,996)
Common stock cash dividends	(91,081)			(91,081)
Ending Balance at Dec. 31, 2018	2,247,573	$ 554,377	1,489,703	946,032	(59,063)	(683,476)
Ending Balance (in shares) at Dec. 31, 2018		170,184
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	226,339			226,339
Other comprehensive income (loss)	58,926				58,926
Stock issued, including related tax benefits	6,362	$ 1,733	2,565			2,064
Stock issued, including related tax benefits (in shares)		883
Stock-based compensation awards	7,413		7,413
Acquisition of treasury stock	(111,457)					(111,457)
Acquisition of treasury stock (in shares)		(6,849)
Common stock cash dividends	(92,980)			(92,980)
Ending Balance at Dec. 31, 2019	$ 2,342,176	$ 556,110	$ 1,499,681	$ 1,079,391	$ (137)	$ (792,869)
Ending Balance (in shares) at Dec. 31, 2019		164,218