v3.10.0.1
Income Taxes (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Sep. 30, 2018
Investments, Owned, Federal Income Tax Note [Line Items]      
U.S. tax reform provisional income tax charge (benefit)   $ 3,100  
Deferred tax liability as a percentage of indefinitely reinvested earnings     24.00%
Minimum      
Investments, Owned, Federal Income Tax Note [Line Items]      
Foreign earnings expected to be indefinitely reinvested     $ 200
Maximum      
Investments, Owned, Federal Income Tax Note [Line Items]      
Foreign earnings expected to be indefinitely reinvested     $ 300
Forecast      
Investments, Owned, Federal Income Tax Note [Line Items]      
U.S. tax reform provisional income tax charge (benefit) $ (389)