Derivative Instruments - Designated as hedging, Financial Performance (Details) (Interest Rate Swap [Member], Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Interest Expense [Member]	Sep. 30, 2011 Interest Expense [Member]	Sep. 30, 2012 Interest Expense [Member]	Sep. 30, 2011 Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Loss Recognized in AOCI on Derivative (Effective Portion, net of tax)	$ (1,000)	$ 0
Amount of Loss Reclassified from AOCI into Earnings			$ (140)	$ 0	$ (250)	$ (360)