Partners' Equity (Tables)

12 Months Ended

Dec. 31, 2012

Distribution Made to Member or Limited Partner [Line Items]

Schedule of Distributions Made to Partners percentages [Table Text Block]

	Total Quarterly Distribution	Marginal Percentage Interest in Distributions
	Target Amount	Unitholders	General Partner
Minimum quarterly distribution	$0.25	98%	2%
First target distribution	Up to $0.275	98%	2%
Second target distribution	above $0.275 up to $0.3125	85%	15%
Third target distribution	above $0.3125 up to $0.375	75%	25%
Thereafter	Above $0.375	50%	50%

Schedule of Allocation of General Partner Interest in Net Income

The following table presents the allocation of the general partner interest in net income for the periods presented below:

	Years Ended December 31,
	2012		2011		2010
	(in thousands)
General partner interest in net income	$	1,464	$	1,287	$	903
General partner incentive distribution	20,986		15,519		11,181
Total general partner interest in net income	$	22,450	$	16,806	$	12,084

Schedule of Distributions Made to Members or Limited Partners, by Distribution

The following table presents the allocation of our regular quarterly cash distributions to the general and limited partners for the periods in which they apply. Our distributions are declared subsequent to quarter end; therefore, the amounts presented do not reflect distributions paid during the periods presented below.

	Years Ended December 31,
	2012		2011		2010
	(In thousands, except per unit data)
General partner interest	$	2,566	$	1,981	$	1,724
General partner incentive distribution	20,986		15,519		11,181
Total general partner distribution	23,552		17,500		12,905
Limited partner distribution	102,222		81,508		73,223
Total regular quarterly cash distribution	$	125,774	$	99,008	$	86,128
Cash distribution per unit applicable to limited partners	$	1.835	$	1.740	$	1.660