Other Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other accrued liabilities
Deferred revenue	$ 7,025	$ 8,617
Accrued health insurance	5,553	4,970
Deferred rent	3,626	3,456
Customer deposits	2,281	2,966
Accrued consulting fees	2,886	2,760
Accrued lab service rebates	332	2,535
Holdbacks and earn-outs	2,250	2,447
Other	20,015	18,018
Other accrued liabilities	$ 43,968	$ 45,769