Annual report pursuant to Section 13 and 15(d)

SUPPLEMENTAL DISCLOSURES ABOUT NATURAL GAS PRODUCING ACTIVITIES - Natural Gas & Condensate Reserve Quantity Information (Details)

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SUPPLEMENTAL DISCLOSURES ABOUT NATURAL GAS PRODUCING ACTIVITIES - Natural Gas & Condensate Reserve Quantity Information (Details)
MMcfe in Thousands, MMcf in Thousands, MBbls in Thousands
12 Months Ended
Dec. 31, 2019
MMcfe
Bcfe
MBbls
MMcf
Dec. 31, 2018
MMcfe
Bcfe
MBbls
MMcf
Dec. 31, 2017
MMcfe
Bcfe
MBbls
MMcf
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]      
Extensions, discoveries and other additions | Bcfe 13 85  
Revisions of previous estimates | Bcfe 4 22  
Purchases of reserves-in-place | Bcfe   1 327
Gas      
Proved Developed and Undeveloped Reserves [Roll Forward]      
Proved reserves, beginning balance | MMcf 264,854 327,118 0
Extensions, discoveries and other additions | MMcf 12,848 22,481 0
Revisions of previous estimates | MMcf 4,737 (84,061) 0
Production | MMcf (13,901) (1,399) (190)
Sale of reserves-in-place | MMcf 0 0 0
Purchases of reserves-in-place | MMcf 0 715 327,308
Proved reserves, ending balance | MMcf 268,538 264,854 327,118
Proved developed reserves: | MMcf 30,699 17,522 5,720
Proved undeveloped reserves: | MMcf 237,839 247,332 321,398
Condensate      
Proved Developed and Undeveloped Reserves [Roll Forward]      
Proved reserves, beginning balance | MBbls 7 10 0
Extensions, discoveries and other additions | MBbls 0 0 0
Revisions of previous estimates | MBbls (6) (2) 0
Production | MBbls (1) (1) 0
Sale of reserves-in-place | MBbls 0 0 0
Purchases of reserves-in-place | MBbls 0 0 10
Proved reserves, ending balance | MBbls 0 7 10
Proved developed reserves: | MBbls 0 7 10
Proved undeveloped reserves: | MBbls 0 0 0
Gas Equivalent      
Proved Developed and Undeveloped Reserve (Energy) [Roll Forward]      
Proved reserve (energy), beginning balance | MMcfe 264,899 327,180 0
Extensions, discoveries and other additions | MMcfe 12,848 22,481 0
Revisions of previous estimates | MMcfe 4,696 (84,072) 0
Production | MMcfe (13,905) (1,405) (191)
Sale of reserves-in-place | MMcfe 0 0 0
Purchases of reserves-in-place | MMcfe 0 715 327,371
Proved reserve (energy), ending balance | MMcfe 268,538 264,899 327,180
Proved developed reserves: | MMcfe 30,699 17,567 5,782
Proved undeveloped reserves: | MMcfe 237,839 247,332 321,398