SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) (Details) MMBoe in Thousands, MBbls in Thousands, Bcf in Thousands	12 Months Ended
	Dec. 31, 2021 MMBoe MBbls Bcf	Dec. 31, 2020 MMBoe MBbls Bcf	Dec. 31, 2019 MMBoe MBbls Bcf	Dec. 31, 2018 MMBoe Bcf MBbls
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Beginning balance | MMBoe	2,278,636	2,150,422	1,934,136
Revision of prior estimates | MMBoe	(61,967)	(57,808)	7,834
Extensions, discoveries and other additions | MMBoe	170,988	328,976	352,731
Production | MMBoe	(167,113)	(142,954)	(144,229)
Sales of reserves in place | MMBoe			(50)
Purchases of reserves in place | MMBoe	672,038
Ending balance | MMBoe	2,892,582	2,278,636	2,150,422
Proved Developed Reserves | MMBoe	2,128,439	1,434,714	1,342,589	1,233,790
Proved Undeveloped Reserves | MMBoe	764,143	843,922	807,833	700,346
Performance Revision
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates | MMBoe	(97,000)	(41,000)	11,000
Proved Undeveloped Reserves Reclassification
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates | MMBoe	(6,000)	(11,000)	(3,000)
Performance Revisions And Drilling
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates | MMBoe	57,000	(61,000)	69,000
Certain Proved Developed Producing Properties
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates | MMBoe	(40,000)	21,000	(58,000)
Pricing And Cost Revisions
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Revision of prior estimates | MMBoe	42,000
Pennsylvania
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]
Extensions, discoveries and other additions | MMBoe	152,000	329,000	353,000
Crude Oil
Proved Developed and Undeveloped Reserves [Roll Forward]
Beginning balance	15	22	120
Revision of prior estimates	10,837	(3)	(48)
Extensions, discoveries and other additions	2,633	0	0
Production	(8,150)	(4)	0
Sales of reserves in place			(50)
Purchases of reserves in place	184,094
Ending balance	189,429	15	22
Proved Developed Reserves	153,010	15	22	107
Proved Undeveloped Reserves	36,419	0	0	13
Natural Gas
Proved Developed and Undeveloped Reserves [Roll Forward]
Beginning balance | Bcf	13,672	12,903	11,604
Revision of prior estimates | Bcf	(538)	(347)	48
Extensions, discoveries and other additions | Bcf	973	1,974	2,116
Production | Bcf	(911)	(858)	(865)
Sales of reserves in place | Bcf			0
Purchases of reserves in place | Bcf	1,699
Ending balance | Bcf	14,895	13,672	12,903
Proved Developed Reserves | Bcf	10,691	8,608	8,056	7,402
Proved Undeveloped Reserves | Bcf	4,204	5,064	4,847	4,202
NGL
Proved Developed and Undeveloped Reserves [Roll Forward]
Beginning balance	0	0	0
Revision of prior estimates	16,797	0	0
Extensions, discoveries and other additions	6,100	0	0
Production	(7,104)	0	0
Sales of reserves in place			0
Purchases of reserves in place	204,822
Ending balance	220,615	0	0
Proved Developed Reserves	193,598	0	0	0
Proved Undeveloped Reserves	27,017	0	0	0