Public Offering of units and Certain Provisions of the Partnership Agreement (Sale of Preferred Units) (Details Textuals) (Preferred Stock [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011
Preferred Stock [Member]
Preferred Units [Line Items]
Net Proceeds From Issuance Of Preferred Limited Partners Units				$ 120.8
Proceeds from Issuance of Preferred Limited Partners Units				125.0
General Partners' Contributed Capital				2.6
Percentage Of Distribution AllocatedTo General Partner				2.00%
Partners' Capital Account, Units, Sold in Private Placement				14,705,882
Preferred Conversion Trading Price				$ 12.75
Preferred Conversion Trading Volume			250,000
Preferred Units, Cumulative Cash Distributions	14.4		14.4		17.2
Distribution Made to Member or Limited Partner, Distributions Declared, Per Unit	$ 0.33
Debt Instrument, Convertible, Beneficial Conversion Feature				$ 22.3
Preferred Stock Dividend Rate Per Dollar Amount Paid In Kind			$ 0.33
Preferred Stock Paid in kind		366,000