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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Income Taxes [Line Items]        
Effective tax rate (0.04%) 0.20% (1.00%) (0.60%)
Net unrecognized tax benefits which would impact effective tax rate if recognized $ 1.0   $ 1.0  
Earliest Tax Year        
Income Taxes [Line Items]        
Open tax year     2015  
Latest Tax Year        
Income Taxes [Line Items]        
Open tax year     2018  
Minimum | Subsidiaries        
Income Taxes [Line Items]        
Effective tax rate     0.00%  
Maximum | Subsidiaries        
Income Taxes [Line Items]        
Effective tax rate     32.00%