Stockholders' Equity (Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Components of Comprehensive Inclome
Net income, as reported	$ 22,460		$ 23,277
Other comprehensive income (loss)
Foreign currency translation adjustment	1,788		2,328
Unrealized gains (losses)
Changes in net unrealized gain (loss) on available-for-sale securities during the period	2,542	[1]	(3,413)	[1]
Realized (gain) loss on available-for-sale securities, net of tax	(1,272)	[1]	230	[1]
Total unrealized gains (losses)	1,270		(3,183)
Total other comprehensive income (loss), net	3,058		(855)
Comprehensive income	$ 25,518		$ 22,422

[1] Stock OptionsA summary of the Company’s stock option activity for all equity incentive plans for the three months ended March 31, 2012 is as follows (in thousands, except per share data and number of years): Number ofShares WeightedAverageExercisePrice WeightedAverageRemainingContractualLife (Years) AggregateIntrinsicValueOutstanding as of December 31, 2011 5,513 $50.80 Granted 767 68.39 Exercised (316) 45.09 Cancelled (35) 59.00 Outstanding as of March 31, 2012 5,929 $53.33 4.1 $80,823Exercisable as of March 31, 2012 3,737 $49.97 3.1 $62,235Restricted Stock and Deferred Issuance Restricted StockA summary of the Company’s restricted stock and deferred issuance restricted stock award activity for the three months ended March 31, 2012 is as follows (in thousands, except per share data): Number ofShares WeightedAverageGrant DateFair ValueUnvested as of December 31, 2011 62 $54.35Granted 3 61.86Vested (3) 51.17Forfeited (1) 53.26Unvested as of March 31, 2012 61 $54.82Performance Stock AwardsA summary of the Company’s performance stock award activity for the three months ended March 31, 2012 is as follows (in thousands, except per share data): Number ofShares Weighted AverageGrant DateFair ValueUnvested as of December 31, 2011 109 $73.92Awarded 108 82.00Vested and issued (46) 72.33Cancelled (1) 72.63Unvested as of March 31, 2012 170 $79.46Beginning in 2010, the Company transitioned from its historical practice of granting certain senior Company employees annual restricted stock awards with time-based vesting provisions only, to granting these employees the right to receive a designated number of shares of Company common stock based on the achiev