Fair Value - Additional Information (Details)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, measurements other than fair value	$ 73,281,000	$ 73,649,000
Fair value, assets, level 2 to level 3 transfers, amount	$ 0	0
Revenue growth rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.007
Revenue growth rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.500
Revenue growth rate | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.049
Discount rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.019
Discount rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.104
Discount rate | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, measurement input	0.080
Software publishing company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, measurements other than fair value	$ 2,100,000	1,000,000.0
Start-up company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, measurements other than fair value	300,000	900,000
Equity method investee
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, measurements other than fair value	6,500,000	2,900,000
Broker dealer exchange memberships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, measurements other than fair value	$ 3,300,000	$ 3,200,000