Debt - Credit Agreement (Details) - USD ($)		12 Months Ended
	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 175,000,000.0
Line of Credit Facility, Commitment Fee Percentage	0.15%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.30%
Number Of Financial Covenants	2
Consolidated Leverage Ratio	3.50
Consolidated Fixed Charge Coverage Ratio	1.25
Total Interest Expense		$ 563,000	$ 2,282,000	$ 6,086,000
Fed Funds Effective Rate Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.005%
Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Senior Credit Facility, applicable margin	0.75%
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Senior Credit Facility, applicable margin	1.75%
Maximum [Member]
Debt Instrument [Line Items]
Consolidated Leverage Ratio	4.50
Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Senior Credit Facility, applicable margin	1.50%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Senior Credit Facility, applicable margin	2.50%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Term		5 years
Total Interest Expense		$ 700,000	$ 1,700,000	$ 6,500,000