Other Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Other accrued liabilities
Deferred revenue	$ 10,807	$ 7,025
Accrued health insurance	5,746	5,553
Deferred rent	4,062	3,626
Accrued consulting fees	2,886	2,886
Holdbacks and earnouts	3,297	2,250
Customer deposits	3,258	2,281
Accrued lab service rebates	289	332
Other	25,925	20,015
Other accrued liabilities	$ 56,270	$ 43,968