Long-term Debt - Principal Balances under Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Total long-term debt	$ 209,774	$ 224,490
Less current portion	10,000	10,000
Long-term portion	199,774	214,490
Term Loan
Line of Credit Facility [Line Items]
Total long-term debt	69,962	82,500
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total long-term debt	$ 139,812	$ 141,990