v3.3.1.900
Disclosures About Oil and Gas Producing Activities - Summary of Changes in Quantities of Proved Oil, NGL and Natural Gas Reserves (Detail)
12 Months Ended
Dec. 31, 2015
MBoe
MBbls
MMcf
Dec. 31, 2014
MBoe
MBbls
MMcf
Dec. 31, 2013
MBoe
MBbls
MMcf
Reserve Quantities [Line Items]      
Production | MMcf (1,530) (1,390) (560)
Proved Developed and Proved Undeveloped Reserves, MBoe Beginning Balance | MBoe 146,248 114,661 95,479
Extensions and discoveries, MBoe | MBoe 34,895 43,247 27,282
Purchases of minerals in place, MBoe | MBoe     109
Production, MBoe | MBoe (5,787) (5,281) (3,517)
Revisions to previous estimates, MBoe | MBoe (8,710) (6,379) (4,692)
Proved Developed and Proved Undeveloped Reserves, MBoe Ending Balance | MBoe 166,646 146,248 114,661
Natural Gas (MMcf) [Member]      
Reserve Quantities [Line Items]      
Proved Developed and Proved Undeveloped Reserves, Beginning Balance | MMcf 300,020 216,002 174,760
Extensions and discoveries | MMcf 79,268 79,454 38,993
Purchases of minerals in place | MMcf     197
Production | MMcf (13,262) (10,773) (6,737)
Revisions to previous estimates | MMcf 9,962 15,337 8,789
Proved Developed and Proved Undeveloped Reserves, Ending Balance | MMcf 375,988 300,020 216,002
NGLs (MBbls) [Member]      
Reserve Quantities [Line Items]      
Proved Developed and Proved Undeveloped Reserves, Beginning Balance 40,907 32,593 29,100
Extensions and discoveries 10,630 10,658 6,531
Purchases of minerals in place     14
Production (1,694) (1,461) (951)
Revisions to previous estimates (357) (883) (2,102)
Proved Developed and Proved Undeveloped Reserves, Ending Balance 49,486 40,907 32,593
Oil (MBbls) [Member]      
Reserve Quantities [Line Items]      
Proved Developed and Proved Undeveloped Reserves, Beginning Balance 55,338 46,067 37,252
Extensions and discoveries 11,054 19,347 14,252
Purchases of minerals in place     62
Production (1,882) (2,024) (1,444)
Revisions to previous estimates (10,014) (8,052) (4,055)
Proved Developed and Proved Undeveloped Reserves, Ending Balance 54,496 55,338 46,067