Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Segment	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | Segment			1
Number of operating segments | Segment			1
Restricted cash	$ 216,000		$ 216,000		$ 0
Debt securities, realized gain (loss)			0
Debt securities, continuous unrealized loss position, 12 months or longer	0		0
Impairment of long-lived assets	0	$ 0	0	$ 0
Right-of-use asset	2,860,000		2,860,000		210,000	$ 300,000
Lease liabilities	554,000		554,000		$ 223,000	$ 300,000
Total annual gross revenues			1,070,000,000.00
Minimum
Summary Of Significant Accounting Policies [Line Items]
Issued nonconvertible debt			1,000,000,000.0
Market value of its stock held by non-affiliates			700,000,000
Stand-by Letter of Credit
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 216,000		$ 216,000