Fair Value Fair Value of Debt (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Reported Value Measurement [Member] | Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 0.0	$ 0.0
Reported Value Measurement [Member] | Loans Payable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0.0	142.5
Reported Value Measurement [Member] | 7.75% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	200.0	200.0
Reported Value Measurement [Member] | 6.625% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	550.0	550.0
Reported Value Measurement [Member] | 6.25% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	400.0	400.0
Reported Value Measurement [Member] | 5.125% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	200.0	200.0
Estimate of Fair Value Measurement [Member] | Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0.0	0.0
Estimate of Fair Value Measurement [Member] | Loans Payable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	0.0	141.1
Estimate of Fair Value Measurement [Member] | 7.75% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	218.5	224.0
Estimate of Fair Value Measurement [Member] | 6.625% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	574.8	583.0
Estimate of Fair Value Measurement [Member] | 6.25% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	415.0	419.0
Estimate of Fair Value Measurement [Member] | 5.125% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 202.0	$ 202.6