Long-term Debt - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 28, 2017	Mar. 27, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 200,000	$ 100,000	$ 400,000	$ 200,000
Unamortized debt issuance costs	3,700,000		3,700,000				$ 2,300,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, average borrowings	$ 223,700,000	$ 109,600,000	253,600,000	93,800,000
Minimum amount borrowed at any one time outstanding			165,000,000	0
Maximum amount borrow at any one time outstanding			$ 336,000,000	$ 220,000,000
Revolving credit facility, weighted-average interest rate	2.30%	1.70%	2.10%	1.80%
Total unused facility fees and letter of credit participation fees	$ 400,000	$ 200,000	$ 600,000	$ 400,000
Revolving Credit Facility | Tenth Amendment
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity	750,000,000		750,000,000
Revolving credit facility, potential additional borrowing capacity	$ 200,000,000		$ 200,000,000
Incurred fees in connection with the Tenth Amendment					$ 1,800,000
Revolving Credit Facility | Ninth Amendment
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity						$ 600,000,000
Revolving credit facility, potential additional borrowing capacity							$ 100,000,000