Income Taxes 6 (Details) R$ in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2018 BRL (R$)
Income Tax Disclosure [Abstract]
Total deferred tax assets, net of valuation allowance	$ 440	$ 440	$ 557
U.S. federal, state and foreign net operating loss carryforwards	734	734	702
Net operating loss carryforwards subject to expiration	526	$ 526
Net operating loss carryforwards expiration period		between 2019 and 2038
Net operating loss carryforwards not subject to expiration	208	$ 208
Change in valuation allowance		(17)	(7)
Unremitted earnings of foreign subsidiaries	2,274	$ 2,274	3,202
Determination of tax on unremitted foreign earnings is not practicable		Due to complexities in the laws of the foreign jurisdictions and the assumptions that would have to be made, it is not practicable to estimate the amount of tax associated with such unremitted earnings.
Liability for uncertain tax positions, Gross	157	$ 157	161
Liability for uncertain tax positions, Current	7	7	16
Deferred tax assets related to uncertain tax positions	10	10	19
Unrecognized tax benefits excluding interest and penalties that would affect effective tax rate	124	124	116
Amount of interest and penalties accrued	24	24	29
(Decrease) increase in amount of interest and penalties		$ (5)	9
Period of unrecognized tax benefit adjustment (in months)		12 months
Income Tax Examination [Line Items]
Income tax expense from continuing operations		$ 545	$ 298	$ 315
Brazilian Tax Authority
Income Tax Examination [Line Items]
Total potential liability from tax assessment including interest and penalties	69	69			R$ 228
Tax Cuts and Jobs Act (Tax Act)
Income Tax Examination [Line Items]
Income tax expense from continuing operations	$ (28)	290
Tax Cuts and Jobs Act (Tax Act) | Taxation of Unremitted Foreign Earnings
Income Tax Examination [Line Items]
Income tax expense from continuing operations		$ 194
Period of tax payments on unremitted foreign earnings (in years)		8 years
Tax Cuts and Jobs Act (Tax Act) | Remeasurement of Deferred Tax Assets and Liabilities
Income Tax Examination [Line Items]
Income tax expense from continuing operations		$ 96