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	Dec. 31, 2012	May 25, 2010	May 24, 2010	Dec. 31, 2009	Sep. 02, 2009
Other Ownership Interests
Series A Preferred Units, shares issued				4,371,586	4,371,586	4,371,586	4,371,586
Preferred units issue discount percentage							4.00%
Preferred units issued at a discount							$ 3
Proceeds from issuance of preferred units, net	77
General Partners' Contributed Capital							2
Series A Preferred Units mandatory redemption date		Sep. 02, 2029
Deducting amounts from partners' capital over the remaining years			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		4,658,700
Series A Preferred Unit
Other Ownership Interests
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
Other Ownership Interests
Distributions paid per unit		$ 0.09125
PIK Distribution
Other Ownership Interests
Distributions paid per unit		$ 0.09125
Maximum
Other Ownership Interests
Maximum Distribution amount for Preferred Units		$ 2
Minimum | Series A Preferred Unit
Other Ownership Interests
Minimum unit conversion request by holders			375,000
Commencing On September 2, 2014 | Series A Preferred Unit
Other Ownership Interests
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 | Minimum | Series A Preferred Unit
Other Ownership Interests
Conversion price, per share minimum			$ 10