Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Jul. 31, 2011	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			$ 2,432.0
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals			2.0
Amount of potential cash payments that could result from unrecognized tax benefits			80.0
Operating Leases, Rent Expense			89.0	$ 97.0	$ 97.0
Convertible Debt
Loss Contingencies [Line Items]
Remaining principal amount of the Convertible Notes			163.0
Debt Instrument, Maturity Date		Jul. 15, 2016
Convertible Notes Interest [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation	[1]		1.0
Maximum [Member] | Unrecorded Unconditional Purchase Obligations Payable in Common Stock Per Year [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			10.0
Maximum [Member] | Common stock
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			$ 32.0

[1] (a)We will be obligated to pay the remaining $163 million principal amount of the Convertible Notes in cash and deliver any excess conversion value in shares of our common stock upon redemption of the Convertible Notes at maturity on July 15, 2016, or upon earlier conversion. See Note 12 for additional information regarding our Convertible Notes.