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Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2016
Jun. 30, 2019
Jun. 30, 2018
Income Taxes [Line Items]          
Effective income tax rate (4.00%) 4.00%   7.00% 3.00%
Provision (benefit) for income taxes $ (130) $ (2,804)   $ 1,838 $ (1,154)
Internal Revenue Service (IRS)          
Income Taxes [Line Items]          
Minimum change in ownership percentage       50.00%  
Measurement of change in ownership period       3 years  
Minimum change in ownership percentage held by shareholders directly or indirectly       5.00%  
Internal Revenue Service (IRS) | Minimum          
Income Taxes [Line Items]          
Income tax, years under examination     2014