SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Standardized Measure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Extractive Industries [Abstract]
Future cash inflows	$ 22,385,385	$ 30,302,480	$ 29,904,474
Future production costs	(10,783,895)	(10,039,294)	(8,702,734)
Future development costs(1)	(1,612,659)	(2,006,167)	(1,766,796)
Future income tax expenses	(2,175,916)	(4,042,787)	(4,166,089)
Future net cash flows	7,812,915	14,214,232	15,268,855
10% annual discount for estimated timing of cash flows	(4,750,760)	(8,353,115)	(8,785,547)
Standardized measure of discounted future net cash flows	3,062,155	5,861,117	6,483,308	$ 5,010,446
Abandonment costs	$ 223,700	$ 212,900	$ 193,500