Supplemental Oil and Gas Information (Unaudited) - Schedule of Net Reserves (Detail)	12 Months Ended
	Dec. 31, 2016 MMcfe bbl MMcf	Dec. 31, 2015 MMcfe bbl MMcf	Dec. 31, 2014 MMcfe bbl MMcf
Oil [Member]
Supplemental Oil And Gas Reserve Information [Line Items]
Proved developed and undeveloped reserves, Beginning of year	90,945	100,258	39,635
Extensions and discoveries	297	2,319	849
Production	(3,883)	(4,087)	(3,135)
Sale of minerals in place	(3,228)	(380)
Revision of previous estimates	(18,390)	(17,297)	(6,186)
Proved developed and undeveloped reserves, End of year	65,741	90,945	100,258
Proved developed reserves, Beginning of year	50,817	54,723	22,429
Proved developed reserves, End of year	45,536	50,817	54,723
Proved undeveloped reserves, Beginning of year	40,128	45,535	17,206
Proved undeveloped reserves, End of year	20,205	40,128	45,535
Purchase of minerals in place		10,132	69,095
Natural Gas [Member]
Supplemental Oil And Gas Reserve Information [Line Items]
Proved developed and undeveloped reserves, Beginning of year | MMcf	461,526	727,216	737,908
Extensions and discoveries | MMcf	288	8,686	12,783
Production | MMcf	(44,776)	(50,875)	(48,721)
Sale of minerals in place | MMcf	(15,227)	(13,731)
Revision of previous estimates | MMcf	(30,795)	(243,898)	12,210
Proved developed and undeveloped reserves, End of year | MMcf	371,016	461,526	727,216
Proved developed reserves, Beginning of year | MMcf	311,147	417,247	427,983
Proved developed reserves, End of year | MMcf	280,035	311,147	417,247
Proved undeveloped reserves, Beginning of year | MMcf	150,379	309,969	309,925
Proved undeveloped reserves, End of year | MMcf	90,981	150,379	309,969
Purchase of minerals in place | MMcf		34,128	13,036
NGL [Member]
Supplemental Oil And Gas Reserve Information [Line Items]
Proved developed and undeveloped reserves, Beginning of year	43,395	59,034	35,794
Extensions and discoveries	42	558	711
Production	(2,283)	(2,820)	(2,498)
Sale of minerals in place	(123)	(758)
Revision of previous estimates	(15,847)	(12,986)	2,676
Proved developed and undeveloped reserves, End of year	25,184	43,395	59,034
Proved developed reserves, Beginning of year	30,315	37,260	17,637
Proved developed reserves, End of year	18,923	30,315	37,260
Proved undeveloped reserves, Beginning of year	13,080	21,774	18,157
Proved undeveloped reserves, End of year	6,261	13,080	21,774
Purchase of minerals in place		367	22,351
Equivalent [Member]
Supplemental Oil And Gas Reserve Information [Line Items]
Proved developed and undeveloped reserves, Beginning of year | MMcfe	1,267,571	1,682,960	1,190,484
Extensions and discoveries | MMcfe	2,320	25,950	22,145
Production | MMcfe	(81,773)	(92,315)	(82,520)
Sale of minerals in place | MMcfe	(35,328)	(20,559)
Revision of previous estimates | MMcfe	(236,225)	(425,587)	(8,862)
Proved developed and undeveloped reserves, End of year | MMcfe	916,565	1,267,571	1,682,960
Proved developed reserves, Beginning of year | MMcfe	797,936	969,141	668,381
Proved developed reserves, End of year | MMcfe	666,786	797,936	969,141
Proved undeveloped reserves, Beginning of year | MMcfe	469,635	713,819	522,103
Proved undeveloped reserves, End of year | MMcfe	249,779	469,635	713,819
Purchase of minerals in place | MMcfe		97,122	561,713