Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	$ 132.4
Long-term debt, fair value	61.7
Long-term debt, face amount	74.3
Payment in Kind (PIK) Note [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, carrying value	31.3	$ 234.6
Long-term debt, fair value	$ 25.1	$ 107.4