Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on A Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent receivable	$ 13,800	$ 11,300
Total assets	52,941	46,757
Contingent consideration liabilities	46,800	15,800
Total liabilities	47,566	17,708
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent receivable	0	0
Total assets	39,141	35,457
Contingent consideration liabilities	0	0
Total liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent receivable	0	0
Total assets	0	0
Contingent consideration liabilities	0	0
Total liabilities	766	1,908
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent receivable	13,800	11,300
Total assets	13,800	11,300
Contingent consideration liabilities	46,800	15,800
Total liabilities	46,800	15,800
Interest Rate Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	766	1,908
Interest Rate Swaps | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	0	0
Interest Rate Swaps | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	766	1,908
Interest Rate Swaps | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	0	0
Money market
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market	39,141	35,457
Money market | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market	39,141	35,457
Money market | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market	0	0
Money market | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market	$ 0	$ 0