Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Accelerated Stock Repurchase Program	Common Stock	Common Stock Accelerated Stock Repurchase Program	Additional Paid-in Capital	Additional Paid-in Capital Accelerated Stock Repurchase Program	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Treasury Stock Accelerated Stock Repurchase Program
Beginning Balance at Dec. 31, 2012	$ 2,081,656		$ 542,093		$ 1,426,267		$ 363,937	$ 5,675	$ (256,316)
Beginning Balance (in shares) at Dec. 31, 2012			199,225
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	161,840						161,840
Other comprehensive loss	(43,016)							(43,016)
Stock issued, including related tax benefits	10,238		$ 2,475		1,377				6,386
Stock issued, including related tax benefits (in shares)			1,427
Stock-based compensation awards	5,330				5,330
Acquisition of treasury stock	(90,927)
Acquisition of treasury stock (in shares)			(8,000)
Common stock cash dividends	(61,934)						(61,934)
Ending Balance at Dec. 31, 2013	2,063,187		$ 544,568		1,432,974		463,843	(37,341)	(340,857)
Ending Balance (in shares) at Dec. 31, 2013			192,652
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	157,894						157,894
Other comprehensive loss	19,619							19,619
Stock issued, including related tax benefits	8,282		$ 987		1,684				5,611
Stock issued, including related tax benefits (in shares)			781
Stock-based compensation awards	5,865	$ (20,000)			5,865	$ (20,000)
Acquisition of treasury stock	(175,255)								(175,255)
Acquisition of treasury stock (in shares)			(14,509)
Common stock cash dividends	(62,927)						(62,927)
Ending Balance at Dec. 31, 2014	1,996,665		$ 545,555		1,420,523		558,810	(17,722)	(510,501)
Ending Balance (in shares) at Dec. 31, 2014			178,924
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	149,502						149,502
Other comprehensive loss	(4,295)							(4,295)
Stock issued, including related tax benefits	10,808		$ 1,586		4,229				4,993
Stock issued, including related tax benefits (in shares)			1,018
Stock-based compensation awards	5,938				5,938
Acquisition of treasury stock	(50,000)								(50,000)
Acquisition of treasury stock (in shares)			(3,976)	1,790
Deferred accelerated stock repurchase payment		$ 0				$ 20,000				$ (20,000)
Common stock cash dividends	(66,724)						(66,724)
Ending Balance at Dec. 31, 2015	$ 2,041,894		$ 547,141		$ 1,450,690		$ 641,588	$ (22,017)	$ (575,508)
Ending Balance (in shares) at Dec. 31, 2015			174,176