Derivative Instruments and Hedging Activities (Details 1) (Interest rate swaps [Member], Derivatives in Cash Flow Hedging Relationships [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2011
Interest rate swaps [Member] | Derivatives in Cash Flow Hedging Relationships [Member]
Summary of Cash Flow Hedges
Amount of Gain or (Loss) Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	$ (0.2)	$ (0.8)	$ (0.3)