Fair Value of Financial Instruments - Earnout Payment Liability (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Details of Level 3 fair value measurements
Additions	$ 5,355
Earnout Payment Liability [Member]
Details of Level 3 fair value measurements
Ending earnout payment liability December 31, 2010	890	1,365
Accretion	128	206
Change in estimate	(916)	(681)
Ending earnout and milestone payment liability December 31, 2012	5,457	890
Estimate of Fair Value, Fair Value Disclosure | Fair Value, Measurements, Recurring [Member] | First 2012 Acquisition [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Acquisition, Contingent Consideration, at Fair Value	1,972
Estimate of Fair Value, Fair Value Disclosure | Fair Value, Measurements, Recurring [Member] | Second 2012 Acquisition [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Acquisition, Contingent Consideration, at Fair Value	3,485
Estimate of Fair Value, Fair Value Disclosure | Fair Value, Measurements, Recurring [Member] | Earnout payment liability at December 31, 2011 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Acquisition, Contingent Consideration, at Fair Value	$ 0