Debt - Summary of Debt (Detail) - USD ($)	Sep. 30, 2021	Mar. 19, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Less: unamortized deferred financing costs	$ (1,485,000)		$ (9,066,000)
Total debt	146,953,000		157,747,000
Less: current portion of debt	(3,125,000)		(4,888,000)
Total long-term debt, net of deferred financing costs	143,828,000		152,859,000
Medium-term Notes | Term Loan due 2026
Debt Instrument [Line Items]
Long-term debt, gross	123,438,000	$ 125,000,000	0
Less: unamortized deferred financing costs		(1,200,000)
Medium-term Notes | Term Loan due 2027
Debt Instrument [Line Items]
Long-term debt, gross	0		166,813,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	$ 25,000,000		$ 0
Less: unamortized deferred financing costs		$ (500,000)