Fair Value Measurements (Fair Value Of Financial Assets And Liabilities) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011		Sep. 30, 2011		Dec. 31, 2010		Mar. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	$ 71,254,000		$ 71,254,000		$ 88,079,000
Fair value of available-for-sale securities	298,760,000		298,760,000		314,204,000
Deferred compensation asset	3,222,000	[1]	3,222,000	[1]	2,748,000	[1]
Forward foreign currency exchange contract asset	1,538,000	[2]	1,538,000	[2]	1,496,000	[2]
Fair value of financial assets, total	374,774,000		374,774,000		406,527,000
Deferred compensation liability	8,733,000	[3]	8,733,000	[3]	5,560,000	[3]
Forward foreign currency exchange contract liability	926,000	[2]	926,000	[2]	1,673,000	[2]
Contingent acquisition consideration payable	38,020,000	[4]	38,020,000	[4]	43,718,000	[4]
Asset retirement obligation	2,947,000	[5]	2,947,000	[5]
Fair value of financial liabilities, total	50,626,000		50,626,000		50,951,000
Percentage of deferred compensation asset included in other assets	96.00%		96.00%		97.00%
Percentage of deferred compensation liability included in other long-term liabilities	93.00%		93.00%		94.00%
Percentage of contingent acquisition consideration payable included in other long-term liabilities	86.00%		86.00%		80.00%
Percentage of contingent acquisition consideration payable included in accounts payable, accrued liabilities and other current assets			14.00%		20.00%
Contingent acquisition consideration payable resulting from acquisition	800,000		5,700,000
Development milestone, paid to former shareholders			3,000,000
Reduction in goodwill amount							300,000
Available-For-Sale Of Securities Short-Term [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	39,685,000		39,685,000		27,457,000
Available-For-Sale Of Securities Short-Term [Member] | Commercial Paper [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Short-Term [Member] | Commercial Paper [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	39,685,000		39,685,000		27,457,000
Available-For-Sale Of Securities Short-Term [Member] | Commercial Paper [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Short-Term [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	81,448,000		81,448,000		80,186,000
Available-For-Sale Of Securities Short-Term [Member] | Corporate Securities [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Short-Term [Member] | Corporate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	81,448,000		81,448,000		80,186,000
Available-For-Sale Of Securities Short-Term [Member] | Corporate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Short-Term [Member] | U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities					48,545,000
Available-For-Sale Of Securities Short-Term [Member] | U.S. Government Agency Securities [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities					0
Available-For-Sale Of Securities Short-Term [Member] | U.S. Government Agency Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities					48,545,000
Available-For-Sale Of Securities Short-Term [Member] | U.S. Government Agency Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities					0
Available-For-Sale Of Securities Short-Term [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	31,987,000		31,987,000		29,845,000
Available-For-Sale Of Securities Short-Term [Member] | Certificates Of Deposit [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Short-Term [Member] | Certificates Of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	31,987,000		31,987,000		29,845,000
Available-For-Sale Of Securities Short-Term [Member] | Certificates Of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | Corporate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	69,073,000		69,073,000		72,329,000
Available-For-Sale Of Securities Long-Term [Member] | Corporate Securities [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | Corporate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	69,073,000		69,073,000		72,329,000
Available-For-Sale Of Securities Long-Term [Member] | Corporate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	48,418,000		48,418,000		29,994,000
Available-For-Sale Of Securities Long-Term [Member] | U.S. Government Agency Securities [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | U.S. Government Agency Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	48,418,000		48,418,000		29,994,000
Available-For-Sale Of Securities Long-Term [Member] | U.S. Government Agency Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	28,149,000		28,149,000		25,848,000
Available-For-Sale Of Securities Long-Term [Member] | Certificates Of Deposit [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Available-For-Sale Of Securities Long-Term [Member] | Certificates Of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	28,149,000		28,149,000		25,848,000
Available-For-Sale Of Securities Long-Term [Member] | Certificates Of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	0		0		0
Overnight Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	36,493,000		36,493,000		51,647,000
Overnight Deposits [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	36,493,000		36,493,000		51,647,000
Overnight Deposits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	0		0		0
Overnight Deposits [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	0		0		0
Money Market Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	34,761,000		34,761,000		36,432,000
Money Market Instruments [Member] | Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	0		0		0
Money Market Instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	34,761,000		34,761,000		36,432,000
Money Market Instruments [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	0		0		0
Quoted Price In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	36,493,000		36,493,000		51,647,000
Fair value of available-for-sale securities	0		0		0
Deferred compensation asset	0	[1]	0	[1]	0	[1]
Forward foreign currency exchange contract asset	0	[2]	0	[2]	0	[2]
Fair value of financial assets, total	36,493,000		36,493,000		51,647,000
Deferred compensation liability	5,511,000	[3]	5,511,000	[3]	2,812,000	[3]
Forward foreign currency exchange contract liability	0	[2]	0	[2]	0	[2]
Contingent acquisition consideration payable	0	[4]	0	[4]	0	[4]
Asset retirement obligation	0	[5]	0	[5]
Fair value of financial liabilities, total	5,511,000		5,511,000		2,812,000
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	34,761,000		34,761,000		36,432,000
Fair value of available-for-sale securities	298,760,000		298,760,000		314,204,000
Deferred compensation asset	3,222,000	[1]	3,222,000	[1]	2,748,000	[1]
Forward foreign currency exchange contract asset	1,538,000	[2]	1,538,000	[2]	1,496,000	[2]
Fair value of financial assets, total	338,281,000		338,281,000		354,880,000
Deferred compensation liability	3,222,000	[3]	3,222,000	[3]	2,748,000	[3]
Forward foreign currency exchange contract liability	926,000	[2]	926,000	[2]	1,673,000	[2]
Contingent acquisition consideration payable	0	[4]	0	[4]	0	[4]
Asset retirement obligation	0	[5]	0	[5]
Fair value of financial liabilities, total	4,148,000		4,148,000		4,421,000
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents	0		0		0
Fair value of available-for-sale securities	0		0		0
Deferred compensation asset	0	[1]	0	[1]	0	[1]
Forward foreign currency exchange contract asset	0	[2]	0	[2]	0	[2]
Fair value of financial assets, total	0		0		0
Deferred compensation liability	0	[3]	0	[3]	0	[3]
Forward foreign currency exchange contract liability	0	[2]	0	[2]	0	[2]
Contingent acquisition consideration payable	38,020,000	[4]	38,020,000	[4]	43,718,000	[4]
Asset retirement obligation	2,947,000	[5]	2,947,000	[5]
Fair value of financial liabilities, total	$ 40,967,000		$ 40,967,000		$ 43,718,000

[1] At September 30, 2011 and December 31, 2010, 96% and 97%, respectively, of the deferred compensation asset balance was included in other assets and the remainder of the balance was included in other current assets on the Company's Condensed Consolidated Balance Sheets.

[2] See Note 9 for further information regarding the Company's derivative instruments.

[3] At September 30, 2011 and December 31, 2010, 93% and 94%, respectively, of the deferred compensation liability balance was included in other long-term liabilities and the remainder was included in accounts payable and accrued liabilities on the Condensed Company's Consolidated Balance Sheets.

[4] At September 30, 2011 and December 31, 2010, 86% and 80%, respectively, of the contingent acquisition consideration payable was included in other long-term liabilities and 14% and 20%, respectively, was included in accounts payable and accrued liabilities.

[5] At September 30, 2011 the asset retirement obligation liability was included in other long-term liabilities.