Equity, Distributions Earned (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Distributions Earned by Limited or General Partners
Total limited partners' distributions	$ 23,959		$ 12,597		$ 46,269		$ 24,191
Total Cash Distributions	26,108		12,960		50,084		24,790
General partner
Distributions Earned by Limited or General Partners
General partner's distributions	522	[1]	260	[1]	1,002	[1]	496	[1]
General partner's IDRs	1,627		103		2,813		103
Total general partner's distributions	2,149	[1]	363	[1]	3,815	[1]	599	[1]
Common
Distributions Earned by Limited or General Partners
Total limited partners' distributions	16,179		6,343		31,014		12,178
Subordinated
Distributions Earned by Limited or General Partners
Total limited partners' distributions	$ 7,780		$ 6,254		$ 15,255		$ 12,013

[1] General partner's distributions (including IDRs) consist of an approximate 2% general partner interest and IDRs, which entitle the general partner to receive increasing percentages, up to 50%, of quarterly distributions in excess of $0.388125 per unit per quarter. See the Annual Report on Form 10-K for the year ended December 31, 2012 for further discussion related to IDRs.