Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2011	$ 781,137	$ 448	$ 616,202	$ (1,225,125)	$ 1,476,550	$ (86,938)
Beginning balance, shares at Dec. 31, 2011		31,590,101
Exercise of stock options and restricted stock units, shares		457,732
Exercise of stock options and restricted stock units, Value	21,927			39,873	(17,946)
Repurchases of Common Stock, Shares		(1,637,827)
Repurchases of Common Stock, Value	(278,672)			(278,672)
Tax benefit resulting from exercise of certain employee stock options	9,318		9,318
Share-based compensation	13,185		13,185
Net earnings	290,847				290,847
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(10,523)					(10,523)
Ending balance at Dec. 31, 2012	827,219	448	638,705	(1,463,924)	1,749,451	(97,461)
Ending balance, shares at Dec. 31, 2012		30,410,006
Exercise of stock options and restricted stock units, shares	398,646	398,646
Exercise of stock options and restricted stock units, Value	19,745			37,870	(18,125)
Repurchases of Common Stock, Shares	(1,321,577)	(1,321,577)
Repurchases of Common Stock, Value	(294,976)			(294,976)
Tax benefit resulting from exercise of certain employee stock options	1,906		1,906
Share-based compensation	12,639		12,639
Net earnings	306,094				306,094
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	62,425					62,425
Ending balance at Dec. 31, 2013	935,052	448	653,250	(1,721,030)	2,037,420	(35,036)
Ending balance, shares at Dec. 31, 2013	29,487,075	29,487,075
Exercise of stock options and restricted stock units, shares	373,431	373,431
Exercise of stock options and restricted stock units, Value	21,047			39,374	(18,327)
Repurchases of Common Stock, Shares	(1,617,499)	(1,617,499)
Repurchases of Common Stock, Value	(414,000)			(414,000)
Tax benefit resulting from exercise of certain employee stock options	3,557		3,557
Share-based compensation	13,611		13,611
Net earnings	338,241				338,241
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(177,913)					(177,913)
Ending balance at Dec. 31, 2014	$ 719,595	$ 448	$ 670,418	$ (2,095,656)	$ 2,357,334	$ (212,949)
Ending balance, shares at Dec. 31, 2014	28,243,007	28,243,007