Debt - Additional Information (Details) - USD ($)				3 Months Ended		6 Months Ended		18 Months Ended
	Apr. 03, 2017	Dec. 02, 2016	Jan. 05, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Apr. 11, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Repayment of debt and revolving credit facility						$ (70,500,000)	$ (22,500,000)
Interest expense				$ 1,500,000	$ 1,200,000	3,000,000	$ 2,800,000
Wells Fargo Bank, National Association
Debt Instrument [Line Items]
Long-term Line of Credit, Gross				200,000,000		200,000,000		$ 200,000,000		$ 260,500,000
Proceeds from lines of credit						10,000,000
Repayment of debt and revolving credit facility						(70,500,000)		(105,000,000)
Long-term debt				194,436,000		194,436,000		194,436,000		254,141,000
Fair value of debt				200,900,000		200,900,000		200,900,000
Wells Fargo Bank, National Association | Secured Debt | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 400,000,000
Annual capital expenditure limitation per Credit Agreement			35,000,000						$ 45,000,000
Maximum allowed non-permitted investments per Credit Agreement			10,000,000						$ 20,000,000
Deferred issuance cost, gross			$ 7,900,000
Wells Fargo Bank, National Association | Secured Debt | Line of Credit | Credit Agreement, Interest Rate Option One | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.50%
Wells Fargo Bank, National Association | Secured Debt | Line of Credit | Credit Agreement, Interest Rate Option One | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			2.25%
Wells Fargo Bank, National Association | Secured Debt | Line of Credit | Credit Agreement, Interest Rate Option Two | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Wells Fargo Bank, National Association | Secured Debt | Line of Credit | Credit Agreement, Interest Rate Option Two | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			1.25%
Wells Fargo Bank, National Association | Secured Debt | Line of Credit | Credit Agreement, Interest Rate Option Two | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Wells Fargo Bank, National Association | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term Line of Credit, Gross				12,500,000		12,500,000		12,500,000		68,000,000
Proceeds from lines of credit						10,000,000
Repayment of debt and revolving credit facility						(65,500,000)
Wells Fargo Bank, National Association | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 200,000,000
Debt instrument, term (in years)			5 years
Proceeds from lines of credit	$ 10,000,000	$ 40,000,000	$ 55,000,000
Wells Fargo Bank, National Association | Revolving Credit Facility | Line of Credit | Minimum
Debt Instrument [Line Items]
Unused capacity, percentage			0.20%
Wells Fargo Bank, National Association | Revolving Credit Facility | Line of Credit | Maximum
Debt Instrument [Line Items]
Unused capacity, percentage			0.35%
Wells Fargo Bank, National Association | Term Loan Facility
Debt Instrument [Line Items]
Long-term Line of Credit, Gross				$ 187,500,000		187,500,000		$ 187,500,000		$ 192,500,000
Proceeds from lines of credit						0
Repayment of debt and revolving credit facility						$ (5,000,000)
Wells Fargo Bank, National Association | Term Loan Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 200,000,000
Debt instrument, term (in years)			5 years
Principal periodic payment, percent, years one and two			5.00%
Principal periodic payment, percent, years three and four			10.00%
Principal periodic payment, percent, year five			15.00%
Proceeds from lines of credit			$ 200,000,000
Wells Fargo Bank, National Association | Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 10,000,000
Wells Fargo Bank, National Association | Letter of Credit | Line of Credit | Minimum
Debt Instrument [Line Items]
Commitment fee percentage			1.50%
Wells Fargo Bank, National Association | Letter of Credit | Line of Credit | Maximum
Debt Instrument [Line Items]
Commitment fee percentage			2.25%
Wells Fargo Bank, National Association | Bridge Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 10,000,000