Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Treasury Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2012		(15,032)
Beginning Balance at Dec. 31, 2012		$ (216,575)	$ 45,376	$ 220,362	$ 1,087,032	$ (69)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends, $.094, $.086 and $.072 per share in 2015, 2014 and 2013, respectively					(5,479)
Stock-Based Compensation				2,250
Reissued Shares (in shares)		739
Reissued Shares		$ 10,825		570
Repurchased Shares (in shares)		(3,502)
Repurchased Shares		$ (100,000)		(25,000)
Net Earnings	$ 120,666				120,666
Foreign Currency Translation Adjustment						5
Ending Balance (in shares) at Dec. 31, 2013		(17,795)
Ending Balance at Dec. 31, 2013		$ (305,750)	45,376	198,182	1,202,219	(64)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends, $.094, $.086 and $.072 per share in 2015, 2014 and 2013, respectively					(6,219)
Share-Based Compensation (in shares)		17
Stock-Based Compensation		$ 300		10,398
Reissued Shares (in shares)		515
Reissued Shares		$ 7,162		(6,290)
Repurchased Shares (in shares)		(1,001)
Repurchased Shares		$ (25,000)		25,000
Net Earnings	78,233				78,233
Foreign Currency Translation Adjustment						(26)
Ending Balance (in shares) at Dec. 31, 2014		(18,264)
Ending Balance at Dec. 31, 2014	1,223,521	$ (323,288)	45,376	227,290	1,274,233	(90)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends, $.094, $.086 and $.072 per share in 2015, 2014 and 2013, respectively					(6,822)
Share-Based Compensation (in shares)		5
Stock-Based Compensation		$ 89		13,605
Reissued Shares (in shares)		107
Reissued Shares		$ 1,726		(783)
Net Earnings	135,709				135,709
Foreign Currency Translation Adjustment						(427)
Ending Balance (in shares) at Dec. 31, 2015		(18,152)
Ending Balance at Dec. 31, 2015	$ 1,366,618	$ (321,473)	$ 45,376	$ 240,112	$ 1,403,120	$ (517)