Supplemental Balance Sheet Information (Schedule Of Other Long-Term Liabilities) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Supplemental Balance Sheet Information [Abstract]
Long-term portion of deferred rent	$ 993	$ 957
Long-term portion of contingent acquisition consideration payable	32,541	34,924
Long-term portion of asset retirement obligation liability	2,947	0
Long-term portion of deferred compensation liability	8,100	5,213
Long-term income taxes payable	5,434	5,584
Deferred tax liabilities	36,517	36,517
Other	2,412	806
Total other long-term liabilities	$ 88,944	$ 84,001	[1]

[1] December 31, 2010 balances were derived from the audited consolidated financial statements.