Revenue Recognition - Revenue by product type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from External Customer [Line Items]
Revenues	$ 17,220	$ 52,215	$ 54,250	$ 92,956
Oil sales
Revenue from External Customer [Line Items]
Revenues	11,976	44,726	41,986	78,310
Natural gas liquid sales
Revenue from External Customer [Line Items]
Revenues	1,762	3,549	4,362	6,942
Natural gas sales
Revenue from External Customer [Line Items]
Revenues	$ 3,482	$ 3,940	$ 7,902	$ 7,704