Income Taxes (Operating Loss Carryforwards) (Details) - USD ($) $ in Millions	Apr. 30, 2016	Apr. 30, 2015
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 25	$ 27
Other Countries [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses in Brazil, valuation allowance	7	8
Brazil [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses in Brazil, valuation allowance	12	12
UK Non Trading Loss [Member]
Operating Loss Carryforwards [Line Items]
Non-trading loss carryforward, valuation allowance	6	$ 7
Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | Other Countries [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses	27
Not Subject to Expiration [Member] | Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | Brazil [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses	35
Not Subject to Expiration [Member] | Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | Other Countries [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses	9
Not Subject to Expiration [Member] | Non-Trading Loss Carryforward [Member] | Foreign Tax Authority [Member] | UNITED KINGDOM
Operating Loss Carryforwards [Line Items]
Non-trading loss carryforward	31
Subject to Expiration [Member] | Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | MEXICO
Operating Loss Carryforwards [Line Items]
Net operating losses	19
Subject to Expiration [Member] | Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | Other Countries [Member]
Operating Loss Carryforwards [Line Items]
Net operating losses	18
Subject to Expiration [Member] | Net Operating Loss Carryforward [Member] | Foreign Tax Authority [Member] | FINLAND
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 51