Earnings (Loss) per Unit - Schedule of earnings per share, basic and diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic and Diluted:
Net income (loss)	$ (7,232)	$ 18,191	$ 68,845	$ 12,965
Weighted-average units (in shares)	119,994	119,994	119,994	119,994
Basic and diluted net earnings (loss) per unit (in dollars per share)	$ (0.06)	$ 0.15	$ 0.57	$ 0.11