Commitments and Contingencies (Details) (USD $)	12 Months Ended			1 Months Ended		12 Months Ended				1 Months Ended			12 Months Ended			12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Jul. 31, 2012 GECC Term Loan item	Sep. 30, 2010 GECC Term Loan	Dec. 31, 2012 GECC Term Loan	Dec. 31, 2011 GECC Term Loan	Dec. 31, 2010 GECC Term Loan	Dec. 31, 2012 GECC Term Loan Maximum	Sep. 30, 2010 GECC existing equipment leases	May 31, 2011 Oxford Term Loan item	Mar. 31, 2011 Oxford Term Loan	Dec. 31, 2012 Oxford Term Loan item	Dec. 31, 2011 Oxford Term Loan	Dec. 31, 2012 Oxford Term Loan Maximum	Dec. 31, 2012 Oxford Term Loan Minimum
Commitments and Contingencies
Number of non-cancelable and renewable operating leases	3
Term Loans
Principal amount of debt issued					$ 15,000,000							$ 2,000,000
Annual interest rate on term loan (as a percent)					9.75%							13.35%
Number of equal monthly payments of principal plus accrued interest				25							36
Additional amount that the Company may draw down in equipment financing															600,000
Number of equal monthly payments of principal plus accrued interest													36
Origination and amendment fees paid						388,000
Exit fee to be paid						525,000
Legal fees and expenses paid						262,000						88,000
Origination, exit and transaction fees and expenses recognized in interest expense						321,000	275,000	67,000
Interest expense recognized						1,400,000	1,500,000	453,000					172,000	192,000
Amount of equipment financing allowed under covenants without any restriction									4,000,000
Repayment of remaining principal outstanding under existing equipment leases	12,000	201,000	1,834,000							787,000
Amount of debt assumption from acquisitions requiring prior written consent under covenants																$ 2,000,000