Financing Arrangement (0.75% Convertible Senior Notes Due 2016) (Details) $ / shares in Units, shares in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2011	Sep. 30, 2016 USD ($) shares	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($)	Jul. 14, 2011 USD ($) $ / shares
Financing Arrangements
Repayments of Convertible Debt			$ 163,000,000	$ 198,000,000
Gain (Loss) on Extinguishment of Debt			0	$ 6,000,000
Convertible Debt
Financing Arrangements
Principal amount					$ 633,000,000
Contractual interest rate of 0.75% Convertible Senior Notes due 2016					0.75%
Debt Instrument, Frequency of Periodic Payment	semiannually
Debt Instrument, Issuance Date	Jul. 14, 2011
Convertible Senior Notes due description	2016
Conversion rate of Notes	31.5075
Face amount of Notes					$ 1,000
Debt Instrument, Convertible, Conversion Price | $ / shares					$ 31.74
Debt Conversion, Original Debt, Amount		$ 136,000,000
Repayments of Convertible Debt		$ 136,000,000	$ 163,000,000
Debt Conversion, Converted Instrument, Shares Issued | shares		2,500	2,900
Debt Conversion, Converted Instrument, Amount		$ 193,000,000	$ 222,000,000
Gain (Loss) on Extinguishment of Debt			$ (300,000)
Shares Received Under Convertible Note Hedge | shares		2,500