v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Jun. 30, 2018
Dec. 31, 2017
Mar. 31, 2018
Mar. 31, 2017
Jun. 30, 2018
Jun. 30, 2017
Income Taxes [Line Items]                  
Effective tax rate 14.00%   23.00%     70.00% 21.00%    
U.S. federal statutory tax rate         35.00%        
Provision for income taxes $ 1,217   $ 1,608     $ 18,096 $ 4,523    
Long-term income taxes 30,669         30,669     $ 13,485
Forecast                  
Income Taxes [Line Items]                  
U.S. federal statutory tax rate       21.00%       28.00%  
Tax Cuts and Jobs Act                  
Income Taxes [Line Items]                  
One-time transition tax on deferred foreign income, cash and other net current assets         15.50%        
One-time transition tax on deferred foreign income, remaining         8.00%        
Provision for income taxes   $ 13,800              
Charge related to transition tax   17,800              
Benefit from impact of changes in tax rate   4,000              
Benefit of deferred taxes related to GILTI   $ 454              
Tax Contingencies and Other Income Tax Liabilities                  
Income Taxes [Line Items]                  
Long-term income taxes $ 14,500         $ 14,500     $ 13,500