CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 157,153	$ 20,188	$ (101,305)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	114,534	102,487	104,298
Impairment of oil and natural gas properties	0	6,775	249,569
Accretion of asset retirement obligations	1,026	892	1,075
Amortization of deferred charges	877	871	935
(Gain) loss on commodity derivative instruments	(26,902)	36,464	(90,288)
Net cash received (paid) on settlement of commodity derivative instruments	15,211	44,789	63,225
Equity-based compensation	33,044	43,138	18,000
(Gain) loss on sale of assets, net	(931)	(4,793)	(4,873)
Changes in operating assets and liabilities:
Accounts receivable	(6,084)	(29,759)	33,586
Prepaid expenses and other current assets	(177)	(180)	95
Accounts payable and accrued liabilities	(3,585)	(23,029)	11,221
Deferred revenue	(2,086)	(870)	(660)
Settlement of asset retirement obligations	(228)	(317)	(143)
NET CASH PROVIDED BY OPERATING ACTIVITIES	281,852	196,656	284,735
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisitions of oil and natural gas properties	(425,667)	(141,136)	(62,278)
Additions to oil and natural gas properties	(58,648)	(80,179)	(54,244)
Purchases of other property and equipment	(207)	(425)	(181)
Proceeds from the sale of oil and natural gas properties	11,102	198	25,705
Proceeds from farmouts of oil and natural gas properties	19,171	0	0
NET CASH USED IN INVESTING ACTIVITIES	(454,249)	(221,542)	(90,998)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of common units of Black Stone Minerals, L.P., net of offering costs	32,458	0	399,087
Proceeds from issuance of Series B cumulative convertible preferred units of Black Stone Minerals, L.P., net of offering costs	293,469	0	0
Distributions to noncontrolling interests	(120)	(111)	(208)
Redemption of Series A redeemable preferred units	(19,704)	(18,461)	(40,747)
Borrowings under credit facility	292,500	349,000	245,600
Repayments under credit facility	(220,500)	(99,000)	(573,600)
Debt issuance costs	(3,075)	(239)	(1,376)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	168,267	21,425	(195,307)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(4,130)	(3,461)	(1,570)
Cash and cash equivalents — beginning of the year	9,772	13,233	14,803
Cash and cash equivalents — end of the year	5,642	9,772	13,233
SUPPLEMENTAL DISCLOSURE
Interest paid	14,761	6,535	5,478
NON-CASH ACTIVITIES
Conversion of Series A redeemable preferred units	6,624	6,064	39,240
Accrued distributions payable to Series A redeemable preferred unitholders	(660)	(1,324)	(2,016)
Accrued distributions payable to Series B cumulative convertible preferred unitholders	(1,925)	0	0
Additions to oil and natural gas properties financed through accounts payable and accrued liabilities	34,247	26,553	21,496
Public offering costs capitalized and offset against proceeds from initial public offering	0	0	7,587
Asset retirement obligations incurred and revisions in estimated costs	391	2,009	272
Accrued distribution equivalent rights	2,694	847	159
Predecessor
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	0	0	(450)
CASH FLOWS FROM FINANCING ACTIVITIES
Distributions to unitholders	0	0	(126,383)
Repurchases of common and subordinated units	0	0	(3,015)
NON-CASH ACTIVITIES
Accrued distributions payable to Predecessor unitholders	0	0	(53,248)
Common and Subordinated Units
CASH FLOWS FROM FINANCING ACTIVITIES
Distributions to unitholders	(194,799)	(175,943)	(81,087)
Repurchases of common and subordinated units	(8,185)	(27,436)	0
Preferred Units
CASH FLOWS FROM FINANCING ACTIVITIES
Distributions to unitholders	$ (3,777)	$ (6,385)	$ (13,578)