Long-Term Debt - Credit Facility (Details)		12 Months Ended
	Jul. 26, 2018 USD ($)	Dec. 31, 2019 USD ($) Lender
Amendment
Revolving credit facility
Maximum consolidated leverage ratio	2.50%
Minimum debt service coverage ratio	2.00%
Minimum EBITDA	$ 50,000,000
Revolving credit facility
Revolving credit facility
Number of additional credit lenders | Lender		5
Maximum borrowing capacity		$ 125,000,000
Minimum EBITDA	50,000,000
Minimum net worth covenant	$ 600,000,000
Reduction in commitment fees (in points)	7.50%
Origination and other costs		3,300,000
Unamortized origination and other costs		200,000
Outstanding debt		0
Remaining borrowing capacity		$ 103,400,000
Revolving credit facility | Minimum
Revolving credit facility
Annual fee (as a percent)		0.15%
Revolving credit facility | Maximum
Revolving credit facility
Annual fee (as a percent)		0.25%
Revolving credit facility | Eurodollar Rate | Minimum
Revolving credit facility
Basis points added		1.125%
Revolving credit facility | Eurodollar Rate | Maximum
Revolving credit facility
Basis points added		2.125%
Revolving credit facility | Base Rate | Minimum
Revolving credit facility
Basis points added		0.125%
Revolving credit facility | Base Rate | Maximum
Revolving credit facility
Basis points added		1.125%
Revolving credit facility | Base Rate | Federal Funds Rate
Revolving credit facility
Basis points added		0.50%
Revolving credit facility | Base Rate | Eurodollar Rate
Revolving credit facility
Basis points added		1.00%
Revolving credit facility | Letter of credit
Revolving credit facility
Maximum borrowing capacity	$ 50,000,000	$ 35,000,000
Outstanding debt		21,600,000
Revolving credit facility | Swingline
Revolving credit facility
Maximum borrowing capacity		$ 35,000,000