Description Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Aug. 31, 2007 Rate	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Aug. 15, 2007 Rate
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		4 years	3 years
Convertible debenture, interest rate	3.25%				3.25%
Convertible debenture, maturity date	Aug. 15, 2037
Net remeasurement gain (loss) on foreign currency translation			$ (3,400,000)
Gains (losses) on foreign currency forward contracts		800,000	1,400,000	(2,900,000)
Notional amount of foreign currency forward contracts		40,200,000
Advertising expenses		$ 10,200,000	$ 17,200,000	$ 12,600,000
Building Improvements [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		10 years
Maximum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Registration term, years		10 years
Average service term, years		2 years
Maximum [Member] | Buildings [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		47 years
Maximum [Member] | Computer Equipment, Purchased Software, Office Equipment, And Furniture And Fixtures [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		5 years
Minimum [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Registration term, years		1 year
Average service term, years		1 year
Minimum [Member] | Buildings [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		35 years
Minimum [Member] | Computer Equipment, Purchased Software, Office Equipment, And Furniture And Fixtures [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (years)		3 years