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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Disclosure [Abstract]              
Provision for (benefit from) income taxes, benefits associated with stock-based awards $ 48.8 $ 9.3 $ 73.1 $ 20.3      
Federal tax at statutory rate (as a percent)     21.00% 21.00% 35.00% 35.00% 35.00%