Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Summary Of Basis Of Presentation And Significant Accounting Policies [Line Items]
Maximum maturity period of cash and cash equivalent			three months
Trading Securities, Realized Gain (Loss)		$ 0		$ 4,980
Trading securities, realized or unrealized gain (loss)	$ 0		$ 0
Potential equivalent common stock excluded	5.4	0.4	4.8	2.9
Trading securities	$ 0		$ 0		$ 0
Other Income, Net [Member]
Summary Of Basis Of Presentation And Significant Accounting Policies [Line Items]
Unrealized gain (loss), trading securities		$ 0		$ 89,405
Minimum [Member]
Summary Of Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period for stock options			1 year
Maximum [Member]
Summary Of Basis Of Presentation And Significant Accounting Policies [Line Items]
Vesting period for stock options			5 years