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Fair Value Measurements - Additional Information (Detail) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments classified as long-term $ 10,146 $ 10,290
Noncontrolling Interest [Member] | Cost-method Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments classified as long-term $ 4,400 $ 4,400