Derivatives (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Derivative [Line Items]
Maximum counterparty loss	$ 3.2
Maximum counterparty loss with netting feature	2.8
Cash Flow Liquid Swap [Member]
Derivative [Line Items]
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	0.6
Unrealized Gain (Loss) on Price Risk Fair Value Hedging Instruments	$ 0.6