Concentration of Credit Risk (Detail) - Customer Concentration Risk [Member]	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue Benchmark [Member]
Concentration Risk [Line Items]
Customer concentration	No customer accounted for more than 10% of revenue	No customer accounted for more than 10% of billings	No customer accounted for more than 10% of billings	No customer accounted for more than 10% of billings
Accounts Receivable [Member]
Concentration Risk [Line Items]
Customer concentration	No customer was more than 10% of accounts receivable	No customer was more than 10% of accounts receivable	No customer was more than 10% of accounts receivable	No customer was more than 10% of accounts receivable

Description of risks that arise due to the volume of business transacted with a particular customer. At a minimum, the description informs financial statement users of the general nature of the risk, but excludes "Information about Major Customers" that may be disclosed elsewhere (for instance, segment disclosures).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6327-108592

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