Leases - Components of Net Investment in Sales-Type Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Sales Type Leases Net Investment In Leases [Abstract]
Current minimum lease payments receivable	$ 702		$ 1,201
Non-current minimum lease payments receivable	347		889
Total minimum lease payments receivable	1,049		2,090
Less: Current unearned revenue	218		365
Less: Non-current unearned revenue	50		163
Net investment in sales-type leases	$ 781	$ 1,600	$ 1,562

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919379-209981

Name:	us-gaap_SalesTypeLeaseLeaseReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant