Debt (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Entity's debt and other obligations
Amount outstanding	$ 1,038.4		$ 1,011.6
Accounts receivable securitization program
Entity's debt and other obligations
Maximum borrowing capacity	150
Amount outstanding			135.0
Proceeds from the accounts receivable securitization program	226.5	222.9
Payments in respect of accounts receivable securitization program	226.5	222.9
Series C convertible senior debentures
Entity's debt and other obligations
Amount outstanding			90.1
Threshold percentage of stock price trigger	120.00%
Threshold trading days	20
Threshold consecutive trading days	30 days
Trading day, reference period	5 days
Estimated cash settlement on debt conversions	39.5
Payment of principal and accrued interest	$ 29.7