Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Total revenues	$ 142,895	$ 122,805	$ 130,769	$ 97,491	$ 153,205	$ 154,641	$ 199,448	$ 173,291	$ 493,960	$ 680,585	$ 726,154
Operating (loss) income	(21,301)	(6,348)	(598)	126	(31,412)	(5,877)	(4,204)	2,185	(28,121)	(39,308)	(32,841)
Loss from continuing operations	(22,039)	(6,891)	(2,365)	(2,689)	(32,097)	(7,201)	(5,479)	1,072	(33,984)	(43,705)	(43,748)
Income (loss) from discontinued operations				(539)	(13,839)	(1,247)	542	(407)	(539)	(14,951)	(9,275)
Net income (loss)	$ (22,039)	$ (6,891)	$ (2,365)	$ (3,228)	$ (45,936)	$ (8,448)	$ (4,937)	$ 665	$ (34,523)	$ (58,656)	$ (53,023)
Common
Basic and diluted loss per unit
Basic and diluted from continuing operations (in dollars per unit)	$ (0.60)	$ (0.18)	$ (0.06)	$ (0.07)	$ (0.88)	$ (0.19)	$ (0.15)	$ 0.03	$ (0.92)	$ (1.19)	$ (0.52)
Basic and diluted income (loss) (in dollars per unit)	(0.60)	(0.18)	(0.06)	(0.09)	(1.26)	(0.23)	(0.13)	0.02	(0.93)	(1.60)	(0.51)
Subordinated
Basic and diluted loss per unit
Basic and diluted from continuing operations (in dollars per unit)	(0.60)	(0.19)	(0.07)	(0.08)	(0.88)	(0.20)	(0.15)	0.03	(0.94)	(1.20)	(0.52)
Basic and diluted income (loss) (in dollars per unit)	$ (0.60)	$ (0.19)	$ (0.07)	$ (0.09)	$ (1.26)	$ (0.23)	$ (0.14)	$ 0.02	$ (0.95)	$ (1.61)	$ (0.51)