Capital - Earnings Per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income (loss)	$ (10,183)	$ (12,269)	$ (8,963)	$ (23,599)
Private perpetual preferred unit distributions	(1,050)	(1,050)	(3,151)	(3,147)
Earnings allocated to unvested units	(114)	(342)	(227)	(985)
Net loss attributable to common unitholders – basic and diluted	$ (11,347)	$ (13,661)	$ (12,341)	$ (27,731)
Denominator:
Weighted average units outstanding - basic (in shares)	277,716,000	280,940,000	277,829,000	285,640,000
Effect of dilutive securities:
Stock-based compensation plans (in share)	0	0	0	0
Weighted average units outstanding - diluted (in shares)	277,716,000	280,940,000	277,829,000	285,640,000
Earnings per share:
Basic (in USD per share)	$ (0.04)	$ (0.05)	$ (0.04)	$ (0.10)
Diluted (in USD per share)	$ (0.04)	$ (0.05)	$ (0.04)	$ (0.10)
Antidilutive securities (in shares)	1,084,264	0	997,811	169,848