Long-Term Debt and Credit Facility - First Lien Credit Facility (Details)			3 Months Ended	12 Months Ended
	Oct. 15, 2015 USD ($)	Aug. 17, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2019 USD ($) letter	Mar. 05, 2020 USD ($)	Dec. 31, 2018 USD ($)
Long-term Debt
Fee on outstanding letters of credit (as a percent)				4.50%
Fronting fee for letters of credit (as a percent)				0.125%
Number of outstanding letters of credit | letter				1
Letters of credit outstanding				$ 50,000
Accrued interest				$ 4,951,000		$ 5,058,000
First Lien Credit Facility
Long-term Debt
Maximum net leverage ratio		7.00
Eurodollar rate | First Lien Credit Facility
Long-term Debt
Applicable margin over reference rate (as a percent)				4.50%
Eurodollar rate | First Lien Credit Facility | Minimum
Long-term Debt
Interest rate (as a percent)				1.00%
Base rate | First Lien Credit Facility
Long-term Debt
Applicable margin over reference rate (as a percent)				3.50%
Term Loan | First Lien Credit Facility
Long-term Debt
Maximum borrowing capacity		$ 435,000,000
Amount repaid	$ 112,500,000		$ 10,000,000
Revolving Credit Facility
Long-term Debt
Amount outstanding				$ 0
Available for borrowing				$ 19,950,000
Revolving Credit Facility | Minimum
Long-term Debt
Unused commitment fee (as a percent)				0.375%
Revolving Credit Facility | Maximum
Long-term Debt
Unused commitment fee (as a percent)				0.50%
Revolving Credit Facility | First Lien Credit Facility
Long-term Debt
Maximum borrowing capacity		$ 40,000,000
Amount drawn to trigger net leverage requirement (as a percent)				50.00%
Amount outstanding				$ 0	$ 0
Revolving Credit Facility | Senior Credit Facility
Long-term Debt
Maximum borrowing capacity					$ 30,000,000
Revolving Credit Facility | Base rate
Long-term Debt
Applicable margin over reference rate (as a percent)				3.50%