Fair Value Measurement - Carrying Amounts and Fair Values of Long-Term Debt Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 178,691	$ 146,576
Current portion of long-term debt	8,438	2,429
Long-term debt	170,253	144,147
Line of Credit | Revolving Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	31,300	0
Fair Value	31,300	0
Term loan facility due 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	147,391	0
Fair Value	144,057	0
Current portion of long-term debt	8,400
Long-term debt	170,300
Term loan and security agreement due 2023 | Line of Credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	0	146,576
Fair Value	$ 0	144,878
Current portion of long-term debt		2,400
Long-term debt		$ 144,100