Fair Value Fair Value of Debt (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	$ 1,180.2	$ 1,010.0
Line of Credit [Member] \| Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	0	0
Line of Credit [Member] \| Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	0	0
Secured Debt [Member] \| Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	379.0	420.3
Secured Debt [Member] \| Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	415.0	473.9
2017 Notes [Member] \| Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	300.0	300.0
2017 Notes [Member] \| Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	295.5	306.0
2019 Notes [Member] \| Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	200.0	0
2019 Notes [Member] \| Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	195.0	0
2014 Notes [Member] \| Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	249.9	249.9
2014 Notes [Member] \| Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	$ 243.8	$ 245.0

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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