Derivatives - Derivative (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Interest Rate Swap [Member]
Derivative [Line Items]
Interest Rate Swap Variable Rate Basis	one-month LIBOR
Interest Rate Cash Flow Hedge Effectiveness Assessment and Measurement	When applicable, we use the shortcut method to assess hedge effectiveness. If the shortcut method is not applicable, we assess effectiveness using the “change-in-variable-cash-flows” method. Our assessments of hedge effectiveness resulted in no ineffectiveness recorded for the quarter and nine months ended September 30, 2013.
Interest Rate Swap Liability	$ 0.6	$ 0.7
Interest Rate Swap Liability, Other Non-Current Liabilities	0.2	0.7
Interest Rate Swap Liability, Other Current Liabilities	$ 0.4	$ 0
Interest Rate Swap Member Effective August 25, 2011 [Member]
Derivative [Line Items]
Interest Rate Swap Fixed Interest Rate	0.825%
Interest Rate Swap Member Effective August 26, 2014 [Member]
Derivative [Line Items]
Interest Rate Swap Fixed Interest Rate	0.75%