Long-term Debt - Principal Balances under Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Total long-term debt	$ 231,719	$ 207,593
Less current portion	10,000	10,000
Long-term portion	221,719	197,593
Term Loan
Line of Credit Facility [Line Items]
Total long-term debt	59,962	64,962
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total long-term debt	$ 171,757	$ 142,631