Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Restricted cash	$ 1,460,000	$ 1,404,000
Allowance for doubtful accounts	0	0
Inventory lower of cost and net realizable value adjustment	150,000	0	$ 340,000
Asset retirement obligation	900,000
Impairment loss recognized	$ 0	0	0
Service contract term	12 months
Capitalized costs associated with development of software	$ 0
Deferred commission	2,400,000	2,100,000
Penalties and interest related to income taxes	$ 0
Change in Accounting Principle, Accounting Standards Update, Adopted	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect	true
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201813Member
Asset Retirement Obligation
Significant Accounting Policies [Line Items]
Accretion expenses	$ 63,000	43,000	$ 33,000
Software
Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Minimum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	2 years
Maximum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	15 years
Irrevocable Standby Letters of Credit
Significant Accounting Policies [Line Items]
Letters of credit drawn, amount	$ 0	0
Collateral for Letters of Credit
Significant Accounting Policies [Line Items]
Restricted cash	$ 1,400,000	900,000
Collateral For Credit Card
Significant Accounting Policies [Line Items]
Restricted cash		$ 500,000