Debt and Interest (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) Rate	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 22, 2016 USD ($)	Dec. 31, 2013 USD ($)
Debt Instrument [Line Items]
Interest expense	$ 1,315	$ 1,711
Revolver borrowings under the credit facility	189,000		$ 185,000
Debt and Capital Lease Obligations	189,000		185,000
Long-term Debt and Capital Lease Obligations, Current	0		0
Long-term Debt and Capital Lease Obligations	$ 189,000		$ 185,000
Line of Credit Facility, Current Borrowing Capacity				$ 450,000
Document Period End Date	Mar. 31, 2017
Line of Credit Facility, Remaining Borrowing Capacity	$ 260,000
Debt, Weighted Average Interest Rate | Rate	2.30%
Amortization of Debt Issuance Costs	$ 107	168
Notional Amount of Interest Rate Derivatives					$ 100,000
Debt Instrument, Interest Rate, Stated Percentage | Rate	0.9475%
Interest Rate Derivative Assets, at Fair Value	$ 200
Long-term Debt, Percentage Bearing Variable Interest, Amount	89,000
Interest Paid	1,305	1,710
Interest Expense [Abstract]
Deferred financing cost	107	168
Interest income	(9)	(14)
Less: amount capitalized for capital projects	(60)	(66)
Total interest expense, net	1,353	$ 1,799
Letter of Credit, Sub-Facility [Member]
Debt Instrument [Line Items]
Revolver borrowings under the credit facility	1,000
Line of Credit Facility, Current Borrowing Capacity				20,000
Swingline, Sub-Facility [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity				20,000
Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				600,000
Line of Credit Facility, Additional Borrowing Capacity				$ 150,000
Variable Rate [Domain]
Debt Instrument [Line Items]
Effect on Future Earnings, Amount	$ 900
High Range Ratio [Member]
Interest Expense [Abstract]
Debt Instrument, Covenant, Total Leverage Ratio				3.50
Debt Instrument Covenant, Interest coverage Ratio				3.00
Low Range Ratio [Member]
Interest Expense [Abstract]
Debt Instrument, Covenant, Total Leverage Ratio				1.00
Debt Instrument Covenant, Interest coverage Ratio				1.00