CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Total	Limited Partner [Member]	General Partner [Member]	Preferred Partner [Member]
Balance at Dec. 31, 2016	$ 25,576	$ 471,180	$ (699,527)	$ 253,923
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	9,913	(3,119)	474	12,558
Equity-based incentive compensation	524	516	8
Distributions	(24,550)	(11,286)	(706)	(12,558)
Capital contributions	104		104
Proceeds from sale of 24,538 common units pursuant to the Employee Unit Purchase Plan	84	84
Balance at Jun. 30, 2017	$ 11,651	$ 457,375	$ (699,647)	$ 253,923

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The amount of ownership interest of different classes of partners in limited partnership.

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Total distributions to each class of partners (i.e., general, limited and preferred partners).

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Total change in each class of partners' capital accounts during the year due to unit-based compensation. All partners include general, limited and preferred partners.

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Amount of cash inflow from issuance of shares under share-based compensation arrangement. Issuance includes, but is not limited to, exercise of stock options and similar instruments.

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The cash inflow from the capital received in cash from a partner in a partnership during the period.

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