Consolidated Statements of Shareholders' Equity (USD $) In Thousands	Total	Treasury Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income Foreign Currency Translation	Accumulated Other Comprehensive (Loss) Income Available-for-Sale Investments	Accumulated Other Comprehensive (Loss) Income Cash Flow Hedges
Beginning Balance at Dec. 31, 2010		$ (77,641)	$ 45,376	$ 201,752	$ 809,084	$ 922	$ (88)	$ 12
Beginning Balance (in shares) at Dec. 31, 2010		(10,665)
Dividends, $.062, $.054 and $.049 per share in 2013, 2012 and 2011, respectively					(4,152)
Stock-Based Compensation				8,385
Reissued Shares (in shares)		737
Reissued Shares		7,493		2,174
Repurchased Shares (in shares)		(5,184)
Repurchased Shares		(129,958)
Net Earnings	113,767				113,767
Foreign Currency Translation Adjustment	(648)					(648)
Change in Net Unrealized Losses on Available-for-Sale Investments	0						88
Change in Net Unrealized Gains on Derivatives Designated as Cash Flow Hedges	(12)							(12)
Ending Balance at Dec. 31, 2011		(200,106)	45,376	212,311	918,699	274	0	0
Ending Balance (in shares) at Dec. 31, 2011		(15,112)
Dividends, $.062, $.054 and $.049 per share in 2013, 2012 and 2011, respectively					(4,710)
Stock-Based Compensation				6,374
Reissued Shares (in shares)		1,317
Reissued Shares		17,662		1,677
Repurchased Shares (in shares)		(1,237)
Repurchased Shares		(34,131)
Net Earnings	173,043				173,043
Foreign Currency Translation Adjustment	30					(343)
Change in Net Unrealized Losses on Available-for-Sale Investments	0
Change in Net Unrealized Gains on Derivatives Designated as Cash Flow Hedges	0
Ending Balance at Dec. 31, 2012	1,136,126	(216,575)	45,376	220,362	1,087,032	(69)	0	0
Ending Balance (in shares) at Dec. 31, 2012		(15,032)
Dividends, $.062, $.054 and $.049 per share in 2013, 2012 and 2011, 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					5
Change in Net Unrealized Losses on Available-for-Sale Investments	0
Change in Net Unrealized Gains on Derivatives Designated as Cash Flow Hedges	0
Ending Balance at Dec. 31, 2013	$ 1,139,963	$ (305,750)	$ 45,376	$ 198,182	$ 1,202,219	$ (64)	$ 0	$ 0
Ending Balance (in shares) at Dec. 31, 2013		(17,795)