Fair Value of Financial Instruments - Significant Unobservable Inputs for Determining Fair Value of Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Measurement Input, Maturity | Quarterly financial statements | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range	1 year
Measurement Input, Maturity | Quarterly financial statements | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range	3 years
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 51,752	$ 30,439
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	29,344	$ 26,094
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	27,544
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Other including start-ups
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 1,800