Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Unrealized gain on available-for-sale marketable securities, net of taxes	$ 873	$ 1,656	$ (533)	$ 457	$ 791	$ 1,416	$ 1,996	$ 2,664
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Proceeds from available for sale municipal bonds							5,979	17,628
Realized loss (less than for the three months ended September 2020)							(100)
Realized gain (less than for the three months ended September 2019)							100
Unrealized gains related to equity securities (less than for the three months ended September 30, 2019)	3,200			100			4,200	5,000
Municipal bonds — available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Proceeds from available for sale municipal bonds	200			10,500			6,000	17,600
Realized loss (less than for the three months ended September 2020)	$ (100)						$ (100)
Realized gain (less than for the three months ended September 2019)				$ 100				$ 100