Fair Value Fair Value of Debt (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
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] | 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] | 7.75% Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	221.0	218.5
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	566.1	574.8
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	412.0	415.0
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	$ 201.7	$ 202.0