Summary of Significant Accounting Policies - Major Customers (Detail)	9 Months Ended
Sep. 30, 2020 customer
Customer Concentration Risk \| Sales Revenue, Net
Summary Of Significant Accounting Policies [Line Items]
Number of major customers that each accounted for more than 10% of total revenues	5
Concentration risk, percentage	96.00%
Credit Concentration Risk \| Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	93.00%
Number of major customers that each accounted for more than 10% of total accounts receivable	5

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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