Cash Distributions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended		0 Months Ended				3 Months Ended
	Feb. 14, 2013	Mar. 31, 2013 item	Dec. 31, 2012	Apr. 24, 2013 Common Unitholders	Feb. 14, 2013 Common Unitholders	Apr. 24, 2013 General Partner	Feb. 14, 2013 General Partner	Mar. 31, 2013 Minimum Quarterly Distribution	Mar. 31, 2013 Minimum Quarterly Distribution Common Unitholders	Mar. 31, 2013 Minimum Quarterly Distribution General Partner	Mar. 31, 2013 First Target Distribution	Mar. 31, 2013 First Target Distribution Common Unitholders	Mar. 31, 2013 First Target Distribution General Partner	Mar. 31, 2013 Second Target Distribution Minimum	Mar. 31, 2013 Second Target Distribution Maximum	Mar. 31, 2013 Second Target Distribution Common Unitholders	Mar. 31, 2013 Second Target Distribution General Partner	Mar. 31, 2013 Third Target Distribution Minimum	Mar. 31, 2013 Third Target Distribution Maximum	Mar. 31, 2013 Third Target Distribution Common Unitholders	Mar. 31, 2013 Third Target Distribution General Partner	Mar. 31, 2013 Thereafter Minimum	Mar. 31, 2013 Thereafter Common Unitholders	Mar. 31, 2013 Thereafter General Partner
Cash Distributions
Period of distribution of available cash after end of each quarter		45 days
Number of quarters of cash reserves to provide funds for distributions to unitholders and General Partner		4
Total Quarterly Distribution Target Amount (in dollars per unit)								$ 0.4625			$ 0.4625			$ 0.4625	$ 0.5375			$ 0.5375	$ 0.6625			$ 0.6625
Marginal Percentage Interest in Distributions									99.17%	0.83%		99.17%	0.83%			86.17%	13.83%			76.17%	23.83%		51.17%	48.83%
Cash Distribution Payment
Per Unit Cash Distribution (in dollars per unit)	$ 0.57		$ 0.57
Incentive Distribution	$ 579
Cash distribution	$ 16,346				$ 15,636		$ 131
Distribution declared
Quarterly cash distribution declared (in dollars per unit)				$ 2.33		$ 0.5825