Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended
		Jul. 31, 2011	Dec. 31, 2015	Mar. 31, 2015	Jul. 14, 2011
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			$ 1,882.0
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals			2.0
Amount of potential cash payments that could result from unrecognized tax benefits			62.0
Convertible Debt
Loss Contingencies [Line Items]
Long-term Debt, Gross			340.0	$ 633.0	$ 633.0
Debt Instrument, Maturity Date		Jul. 15, 2016
Convertible Notes Interest [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation	[1]		2.0
Unrecorded Unconditional Purchase Obligation Payable in Common Stock Per Year | Maximum
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			10.0
Unrecorded Unconditional Purchase Obligation Payable in Common Stock | Maximum
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			$ 32.0

[1] We will be obligated to pay the $340 million principal amount of the Notes in cash and any excess conversion value in shares of our common stock upon redemption of the Notes at maturity on July 15, 2016, or upon earlier conversion. During the quarter ended December 31, 2015, the Sales Price Condition was met and as a result, the Notes are currently convertible at the option of the holder though April 2, 2016. During the quarter ending March 31, 2016, we expect to settle at least $177 million in cash and a number of shares of our common stock equal in value to the excess conversion value. See Note 10 for additional information regarding our Notes.