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Goodwill and Identifiable Intangible Assets - Significant Assumptions Used to Estimate the Fair Values of Tradenames Impaired (Parenthetical) (Detail) - Long-term Revenue Growth Rate [Member]
 9 Months Ended 12 Months Ended
Sep. 30, 2020
Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Long-term revenue growth rate projection period 10 years 10 years
Alternative Investment, Type [Extensible List] us-gaap:TradeNamesMember us-gaap:TradeNamesMember