Earnings Per Share - Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified			3 Months Ended				3 Months Ended							3 Months Ended
	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2013 Common Stock	Jun. 30, 2012 Common Stock	Mar. 31, 2012 Common Stock	Jun. 30, 2013 TEU Senior Amortizing Notes Maturing August 2013 [Member]	Jun. 30, 2012 7 1/2% Mandatory Convertible Subordinated Notes [Member] Convertible Subordinated Debt	Mar. 31, 2012 7 1/2% Mandatory Convertible Subordinated Notes [Member] Convertible Subordinated Debt	Jun. 30, 2013 Tangible Equity Units	Sep. 30, 2012 Tangible Equity Units TEUs	Jul. 17, 2012 Tangible Equity Units Senior Notes TEUs	Mar. 31, 2012 Tangible Equity Units Senior Notes TEUs	May 31, 2010 Tangible Equity Units Senior Notes TEUs	Jun. 30, 2013 Subsequent Event Common Stock	Mar. 31, 2013 Subsequent Event Common Stock	Dec. 31, 2012 Pre-adjustment shares [Member]	Jun. 30, 2013 Post-adjustment Shares [Member]
Earnings Per Share [Line Items]
Debt Conversion, Converted Instrument, Shares Issued			600,000	2,200,000	2,200,000									400,000	400,000
Value of convertible debt exchanged for common stock							$ 48.1	$ 48.1
Shares exchanged for common stock					2,800,000
Tangible Equity Units (TEUs) issued during period, (units)										4,600,000	4,600,000	2,800,000	3,000,000
Tangible Equity Units outstanding						18,100,000			4,800,000
Shares of common stock issuable upon conversion									8,100,000
Stock Issued During Period, Shares, Conversion of Convertible Securities									8,100,000
Common Stock, Shares Authorized	63,000,000	63,000,000														100,000,000	63,000,000