Long-term Debt - Principal Balances under Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Total long-term debt	$ 210,218	$ 224,490
Less current portion	10,000	10,000
Long-term portion	200,218	214,490
Term Loan
Line of Credit Facility [Line Items]
Total long-term debt	67,462	82,500
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total long-term debt	$ 142,756	$ 141,990