Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	31.00%		37.00%	28.00%	37.00%
Provision for income taxes	$ 87		$ 70	$ 109	$ 166
U.S. federal statutory tax rate	21.00%		35.00%	21.00%	35.00%
Tax Cuts and Jobs Act, Accounting Complete	true			true
Provisional deemed repatriation tax		$ 10
Deferred tax assets	$ 2,600			$ 2,600		$ 1,600
Net deferred income tax liability	$ 5,400			$ 5,400		$ 5,300

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Tax cuts and jobs act of 2017 change in tax rate income tax expense benefit deemed repatriation tax provisional.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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