Composition of Certain Financial Statement Captions (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other current assets:
Acquisition related escrows	$ 36,967	$ 6,167
Other current assets	4,281	899
Total other current assets	41,248	7,066	21,656
Accounts payable and accrued liabilities:
Accrued salaries, benefits and other related costs	66,354	60,013
Escrow liabilities	30,899	135
Other current liabilities	65,739	51,847
Total accounts payable and accrued liabilities	162,992	111,995
Other liabilities:
Unrecognized tax benefits , including interest and penalty	22,567	30,833
Deferred rent	13,575	14,292
Other liabilities	25,724	45,088
Total other liabilities	$ 61,866	$ 90,213