Debt (Details) - USD ($)		3 Months Ended	9 Months Ended
	Jul. 31, 2015	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Credit facility
Accretion of debt financing costs included in interest expense		$ 600,000	$ 1,700,000
Credit Facility | Alternate base rate
Credit facility
Margin of interest (as a percent)	3.75%
Credit Facility | LIBOR
Credit facility
Margin of interest (as a percent)	4.75%
Variable rate base minimum (as a percent)	1.00%
Term Loan
Credit facility
Total Term Loan outstanding		408,807,000	408,807,000	$ 410,536,000
Less: Amounts due within one year		4,250,000	4,250,000	4,250,000
Total long-term debt due after one year		404,557,000	404,557,000	$ 406,286,000
Debt issuance costs incurred	$ 12,900,000
Deferred issuance costs, net		10,900,000	10,900,000
Face amount	$ 425,000,000
Amortization per year (as a percent)	1.00%
Revolving loan
Credit facility
Debt issuance costs incurred	$ 1,300,000
Maximum borrowing available	25,000,000
Letter-of-credit sub-facility
Credit facility
Maximum borrowing available	$ 10,000,000	900,000	900,000
Letters of credit, amount outstanding		$ 0	$ 0