Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Revenue - Additional Information (Detail)	3 Months Ended		9 Months Ended
Revenue - Additional Information (Detail)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Category	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Revenue [Line Items]
Number of categories \| Category			3
Remaining performance obligations	$ 0		$ 0
Recognized revenue	1,500,000	$ 1,200,000	9,600,000	$ 11,700,000
Other Than Maintenance Services [Member]
Revenue [Line Items]
Remaining performance obligations	$ 16,500,000		$ 16,500,000		$ 13,600,000