Long-term Debt - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jul. 10, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 28, 2017	Mar. 27, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Amortization of debt issuance costs		$ 200,000	$ 100,000	$ 600,000	$ 300,000
Unamortized debt issuance costs		3,500,000		3,500,000				$ 2,300,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, average borrowings		$ 465,900,000	$ 228,800,000	325,200,000	139,100,000
Minimum amount borrowed at any one time outstanding				165,000,000	0
Maximum amount borrow at any one time outstanding				$ 605,000,000	$ 280,000,000
Revolving credit facility, weighted-average interest rate (percent)		2.50%	1.70%	2.30%	1.70%
Total unused facility fees and letter of credit participation fees		$ 200,000	$ 100,000	$ 800,000	$ 500,000
Revolving Credit Facility | Tenth Amendment
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity		750,000,000		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
Farner-Bocken Company
Debt Instrument [Line Items]
Cash paid at closing	$ 169,000,000