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Income Taxes - Additional Information (Details) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Income Tax Disclosure [Abstract]          
Provision for income taxes $ 0 $ 0 $ 0 $ 0  
Unrecognized tax benefits that would impact effective tax rate $ 0   $ 0   $ 0