Financing Arrangement (Convertible Note Hedge and Warrants Issuance) (Details) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2011 USD ($)	Sep. 30, 2016 $ / shares shares	Sep. 30, 2016 $ / shares shares	Jul. 14, 2011 $ / shares shares
Financing Arrangements
Greater Than Or Equal to Trading Days For Automatic Exercise of Warrants			60
Investment Warrants Expiration Date			Oct. 17, 2016
Convertible Note Hedge [Member]
Financing Arrangements
Amount paid for Convertible Note Hedge | $	$ 107
Warrants
Financing Arrangements
Strike price of warrants | $ / shares				$ 41.14
Proceeds from Warrants transaction | $	$ 65
Warrants - Underlying
Financing Arrangements
Shares covered by warrants issuance | shares				19,900
Warrants - Estimated
Financing Arrangements
Shares covered by warrants issuance | shares		10,300	10,300
Convertible Debt
Financing Arrangements
Debt Conversion, Converted Instrument, Shares Issued | shares		2,500	2,900
Share Price | $ / shares		$ 85.40	$ 85.40
Debt Instrument, Convertible, Conversion Price | $ / shares				$ 31.74