Series A Preferred Units (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2009	Dec. 31, 2011 quarters	May 25, 2010	Sep. 02, 2009
Other Ownership Interests [Line Items]
Preferred stock, shares issued				4,371,586
Preferred units issued at a discount				4.00%
Discount related to the issuance of preferred partner units, amount				$ 3.2
Preferred units issuance costs				0.2
Proceeds from issuance of preferred units, net	76.6
General Partners' Contributed Capital				1.6
Mandatorily redeemable all accrued but unpaid distributions		80
Distributions paid per unit		$ 0.445
Maximum distribution made to member or Limited Partner, period of consecutive fiscal quarters		20
Series A preferred units convertible to common units		4,632,389
Series A convertible redeemable preferred units, fair value			70.8
Preferred Units Net Proceeds From Issuance Excluding Embedded Derivative Value				47.7
Series A Preferred Unit [Member]
Other Ownership Interests [Line Items]
Series A price per unit				$ 18.30
Distributions paid per unit		$ 0.35375
Increase in distribution made to member or Limited Partner distributions, declared per unit, due to covenant default		$ 0.1825
Accumulated and unpaid distributions, quarterly accrual interest rate percentage		2.432%
Covenant default, accumulated and unpaid distributions, quarterly accrual interest rate percentage		3.429%
Preferred Stock, Redemption Price Per Share		$ 18.30
Due to change of control, required purchase offer as percentage of liquidation value		101.00%
Cash event, required purchase offer as percentage of liquidation value		120.00%
Common Unit Distribution [Member]
Other Ownership Interests [Line Items]
Distributions paid per unit		$ 0.09125
PIK Distribution [Member]
Other Ownership Interests [Line Items]
Distributions paid per unit		$ 0.09125
Maximum [Member]
Other Ownership Interests [Line Items]
Maximum Distribution amount for Preferred Units		$ 1.6
Maximum [Member] | Series A Preferred Unit [Member]
Other Ownership Interests [Line Items]
Conversion Price Adjusted Common Unit Issue Price		$ 16.47
Minimum [Member] | Series A Preferred Unit [Member]
Other Ownership Interests [Line Items]
Minimum unit conversion request by holders		375,000
Commencing On September 2, 2014 [Member] | Series A Preferred Unit [Member]
Other Ownership Interests [Line Items]
Percenatge component of denominator, used in conversion ratio when conversion price is less than volume-weighted average trading price		91.00%
Conversion requirements, daily volume-weighted average trading price over conversion price, percentage		150.00%
Conversion price requirements met, number of trading days		20
Range of trailing trading days, assess conversion price requirements		30
Commencing On September 2, 2014 [Member] | Minimum [Member] | Series A Preferred Unit [Member]
Other Ownership Interests [Line Items]
Conversion price, per share minimum		$ 10