Partners' Equity - Income (loss) per unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net loss	$ (38,474)	$ (16,488)	$ (267,328)	$ (15,960)
Distributions to preferred unitholders	4,750	2,194	9,500	2,194
Net loss available to unitholders	$ (43,224)	$ (18,682)	$ (276,828)	$ (18,154)
Weighted average number of units outstanding (in shares)	68,897,000	57,372,000	68,909,000	57,341,000
Effect of dilutive securities:
Restricted and phantom units (in shares)	0	0	0	0
Weighted average units and potential common units outstanding (in shares)	68,897,000	57,372,000	68,909,000	57,341,000
Basic and diluted loss per unit (in dollars per share)	$ (0.63)	$ (0.33)	$ (4.02)	$ (0.32)
Phantom share units (PSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive restricted units excluded from computation of EPS	862,064	323,965	862,064	323,965
Restricted stock units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive restricted units excluded from computation of EPS	508,830	264,097	508,830	264,097