Financing Arrangements (Redemption of 10.375% Senior Discount Notes) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			0 Months Ended	3 Months Ended	9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012	Jan. 26, 2011 10.375% Senior Discount Notes	Dec. 31, 2011 10.375% Senior Discount Notes	Jun. 30, 2012 10.375% Senior Discount Notes	Dec. 31, 2012 10.375% Senior Discount Notes
Debt Instrument [Line Items]
Face amount of notes issued						$ 747.2
Cash proceeds from issuance of notes						444.7
Extinguishment of Debt Disclosures [Abstract]
Accreted value of notes redeemed							450.0
Payment of redemption premiums on notes			0	27.6			27.6
Long-term debt	2,703.2		2,703.2		2,706.6		14.7	9.9	10.4
Debt extinguishment costs	0	0	0	38.9			38.9
Debt extinguishment costs, net of taxes							25.3
Amount of notes redeemed								$ 6.0