Income Taxes 6 (Details) BRL in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 BRL
Income Tax Disclosure [Abstract]
Total deferred tax assets, net of valuation allowance	$ 557	$ 600
U.S. federal, state and foreign net operating loss carryforwards	702	671
Net operating loss carryforwards subject to expiration	$ 477
Net operating loss carryforwards expiration period	between 2018 and 2037
Net operating loss carryforwards not subject to expiration	$ 225
Change in valuation allowance	(7)	11
Unremitted earnings of foreign subsidiaries	$ 3,202	2,987
Determination of tax on unremitted foreign earnings is not practicable	It is not practicable to determine the amount of tax associated with such unremitted earnings.
Liability for uncertain tax positions, Gross	$ 161	163
Liability for uncertain tax positions, Current	16	1
Deferred tax assets related to uncertain tax positions	19	17
Unrecognized tax benefits that would affect effective tax rate	116	119
Amount of interest and penalties accrued	29	20
Increase (decrease) in amount of interest and penalties	$ 9	$ (8)
Period of unrecognized tax benefit adjustment (in months)	12 months
Brazilian Tax Authority
Income Tax Examination [Line Items]
Total potential liability from tax assessment including interest and penalties	$ 58		BRL 180