Debt - Components of Debt (Details) - USD ($) $ in Thousands	9 Months Ended		18 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Components of beginning debt balance [Abstract]
Long term debt, current portion, net of deferred issuance cost at beginning of period	$ 13,410			$ 8,410
Long-term debt, net	178,923			245,731
Debt Borrowing, Repayment, Amortization during period [Abstract]
Repayment of debt and revolving credit facility	(100,000)	$ (25,000)
Amortization of deferred issuance cost	1,192	$ 1,192
Components of ending debt balance [Abstract]
Long-term debt, current portion, net	13,410			8,410
Long term debt, net of deferred issuance cost at end of period	178,923			245,731
Wells Fargo Bank, National Association
Components of beginning debt balance [Abstract]
Debt under credit facilities at beginning of period	260,500
Deferred issuance cost, net at beginning of period	(6,359)
Total Debt, net of deferred issuance cost at beginning of period	254,141
Long term debt, current portion, net of deferred issuance cost at beginning of period	13,410			8,410
Long-term debt, net	178,923			245,731
Debt Borrowing, Repayment, Amortization during period [Abstract]
Proceeds from lines of credit	37,000
Deferred issuance cost, gross	0
Increase in borrowings net of deferred issuance cost	37,000
Repayment of debt and revolving credit facility	(100,000)		$ (134,500)
Amortization of deferred issuance cost	1,192
Decrease in repayment/amortization net of deferred issuance cost	(98,808)
Components of ending debt balance [Abstract]
Debt under credit facilities at end of period	197,500
Deferred issuance cost, net at end of period	(5,167)
Total Debt, net of deferred issuance cost at end of period	192,333
Long-term debt, current portion, net	13,410			8,410
Long term debt, net of deferred issuance cost at end of period	178,923			$ 245,731
Wells Fargo Bank, National Association | Term Loan Facility
Components of beginning debt balance [Abstract]
Debt under credit facilities at beginning of period	192,500
Debt Borrowing, Repayment, Amortization during period [Abstract]
Proceeds from lines of credit	0
Repayment of debt and revolving credit facility	(7,500)
Components of ending debt balance [Abstract]
Debt under credit facilities at end of period	185,000
Wells Fargo Bank, National Association | Revolving Credit Facility
Components of beginning debt balance [Abstract]
Debt under credit facilities at beginning of period	68,000
Debt Borrowing, Repayment, Amortization during period [Abstract]
Proceeds from lines of credit	37,000
Repayment of debt and revolving credit facility	(92,500)
Components of ending debt balance [Abstract]
Debt under credit facilities at end of period	$ 12,500