Revolving Credit Facility and Long-Term Debt - Principal Balances under Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Feb. 23, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Total debt	$ 277,940		$ 324,373
2017 Debt facility	6,962	$ 7,000	0
Less debt issuance costs	(522)		(627)
Less current portion	16,962		10,000
Long-term portion	260,978		314,373
Term Loan
Line of Credit Facility [Line Items]
Total debt	87,500		145,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total debt	$ 184,000		$ 180,000