Long-Term Debt, Credit Facility (Details) - USD ($) $ in Thousands		9 Months Ended
	Apr. 21, 2017	Sep. 30, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Long term debt outstanding		$ 149,019	$ 210,343
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Availability under the revolving credit facility under most restrictive covenant		$ 92,800
Prior Credit Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Initiation date		Jun. 08, 2012
Credit Agreement [Member]
Line of Credit Facility [Line Items]
Initiation date		Apr. 21, 2017
Maturity date		Apr. 21, 2022
Credit Agreement [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Unused commitment fee percentage	0.20%
Credit Agreement [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Unused commitment fee percentage	0.50%
Credit Agreement [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Credit Agreement [Member] | LIBOR [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Variable rate basis	0.00%
Margin rate	1.50%
Credit Agreement [Member] | LIBOR [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate	2.75%
Credit Agreement [Member] | One-Month LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Credit Agreement [Member] | Base Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Margin rate	0.50%
Credit Agreement [Member] | Base Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate	1.75%
Credit Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 100,000
Credit Agreement [Member] | Letters of Credit Sub Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000
Credit Agreement [Member] | Swingline Sub Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	25,000
Credit Agreement [Member] | Term Loan Facility A [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount	70,000
Credit Agreement [Member] | Delayed Draw Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 150,000
Long term debt outstanding		$ 0
Credit Agreement [Member] | Delayed Draw Term Loan Facility [Member] | First 12 Quarters Following the Closing [Member]
Line of Credit Facility [Line Items]
Periodic principal payment as percentage of aggregate principal amount	1.25%
Credit Agreement [Member] | Delayed Draw Term Loan Facility [Member] | Remaining Quarters Prior to Maturity [Member]
Line of Credit Facility [Line Items]
Periodic principal payment as percentage of aggregate principal amount	1.875%
Credit Agreement [Member] | Uncommitted Incremental Accordion Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 100,000