Commitments And Contingencies (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended
	May 14, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Commitments And Contingencies [Line Items]
Tenant allowance total		$ 8,400,000
Future rental payments due		100,794,000
Rent expense under operating leases		11,400,000	8,800,000	5,300,000
Amount awarded to plaintiff	1,400,000
Litigation settlement date		April 2011
Accrued Expenses [Member]
Commitments And Contingencies [Line Items]
Deferred rent		1,400,000
Other Long-Term Liabilities [Member]
Commitments And Contingencies [Line Items]
Deferred rent		5,100,000
Existing Lease Arrangement [Member]
Commitments And Contingencies [Line Items]
Lease expiration date		May 31, 2013
New Lease Arrangement [Member]
Commitments And Contingencies [Line Items]
Lease commencement date		July 1, 2011
Lease expiration date		December 31, 2023
Number of additional lease terms		2
Additional lease term (in years)		5
Future rental payments due		$ 75,800,000
Other Lease Arrangements [Member]
Commitments And Contingencies [Line Items]
Lease expiration date		2020