Long-Term Borrowings (Details) (USD $) In Millions	3 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Nov. 30, 2010
Long-Term Borrowings
Senior unsecured notes due 2018 (net of $1.2 million and $1.3 million of unamortized discount at June 30, 2011 and March 31, 2011, respectively	$ 298.8	$ 298.7
Capital leases and other obligations	54.4	56.2
Total	353.2	354.9
Less current maturities of capital leases and other obligations (included in accrued liabilities)	(19.3)	(19.3)
Long-term borrowings	333.9	335.6
Long Term Borrowings (Textuals) [Abstract]
Unamortized discount	1.2	1.3
Amount of unsecured revolving credit facility			400.0
Expiration date of credit facility	Nov. 30, 2014
Maximum amount of credit facility			600.0
Provision for swing line loans (maximum)			25.0
Provision for standby letters of credit (maximum)			$ 50.0
Interest periods for revolving loans under the credit facility	1,2,3 or 6 months