Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Restricted cash	$ 1,404,000	$ 1,933,000
Allowance for doubtful accounts	0	0
Inventory lower of cost and net realizable value adjustment	0	340,000	$ 911,000
Asset retirement obligation	900,000
Impairment loss recognized	$ 0	0	0
Service contract term	12 months
Deferred commission	$ 2,100,000	3,900,000
Penalties and interest related to income taxes	0
Operating lease, right-of-use assets	11,720,000	0
Operating lease, liabilities	12,743,000
ASU 2016-02
Significant Accounting Policies [Line Items]
Operating lease, right-of-use assets				$ 11,900,000
Operating lease, liabilities				$ 12,600,000
Asset Retirement Obligation
Significant Accounting Policies [Line Items]
Accretion expenses	$ 43,000	33,000	$ 40,000
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	900,000	900,000
Collateral For Credit Card
Significant Accounting Policies [Line Items]
Restricted cash	$ 500,000	$ 1,000,000