Borrowings - Term Loan and Master Lease Agreement (Details)				12 Months Ended			48 Months Ended
	Dec. 30, 2015 USD ($) installment	Jul. 29, 2013 USD ($)	Jun. 01, 2011 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	May 31, 2015 USD ($)	Aug. 10, 2012 USD ($)
Master Lease Agreement
Obligations under capital lease				$ 3,269,000	$ 8,961,000
Interest expense including amortization of debt issuance costs and net settlement payments on interest rate swaps				2,200,000	$ 1,800,000	$ 2,300,000
H-P Loan
Term Loan
Term of Term Loan Agreement	5 years
Term debt	$ 3,600,000
Number of quarterly installments for payable of remaining loan principal | installment	20
Repayment of principal in quarterly installments	$ 195,000
Accrued interest (as a percent)	2.95%
Schedule of remaining principal payments
2017				694,000
2018				715,000
2019				737,000
2020				759,000
2021				193,000
Total				3,098,000
Master Lease Agreement
Interest, fixed rate (as a percent)	2.95%
Equipment Loan Agreement
Term Loan
Term of Term Loan Agreement			4 years
Term debt			$ 25,500,000
Repayment of principal in quarterly installments							$ 530,600
Accrued interest (as a percent)							3.00%
Interest Rate							one month LIBOR rate for dollar deposits
Master Lease Agreement
Interest, fixed rate (as a percent)							3.00%
Master Lease Agreement
Term Loan
Accrued interest (as a percent)		3.39%
Master Lease Agreement
Master lease facility, amount				$ 5,000,000				$ 25,000,000
Obligations under capital lease		$ 21,200,000
Interest, fixed rate (as a percent)		3.39%
Term of capital lease		48 months		48 months
Ending purchase price of underlying assets		$ 1						$ 1
Amount outstanding under Credit Agreement				$ 3,300,000