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Major Customers - Additional Information (Detail) - Customer Concentration Risk [Member] - Customer
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]    
Number of customers 2 2
Sales Revenue, Net [Member] | 2 Customers [Member]    
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]    
Customers accounted from total revenue 71.00% 91.00%