Accumulated Other Comprehensive Income (Loss) (Details) (Reclassification out of Accumulated Other Comprehensive Income [Member], Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) / Gain Reclassified from Accumulated OCI into Income (Effective Portion)	$ (0.2)
Tax (expense) benefit	0.1
Reclassifications for the period ended December 31, 2011	(0.1)
Interest Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) / Gain Reclassified from Accumulated OCI into Income (Effective Portion)	$ (0.2)