CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
REVENUE
Oil and condensate sales	$ 37,262	$ 34,553	$ 77,736	$ 61,801
Natural gas and natural gas liquids sales	49,903	21,607	97,604	46,719
Gain (loss) on commodity derivative instruments	22,003	(30,733)	44,728	(20,107)
Lease bonus and other income	11,356	15,142	25,038	16,537
TOTAL REVENUE	120,524	40,569	245,106	104,950
OPERATING (INCOME) EXPENSE
Lease operating expense	4,148	4,283	8,337	9,172
Production costs and ad valorem taxes	11,863	7,012	23,765	14,074
Exploration expense	46	629	608	637
Depreciation, depletion, and amortization	28,900	29,202	55,279	50,923
Impairment of oil and natural gas properties	0	679	0	6,775
General and administrative	17,481	18,134	34,693	35,535
Accretion of asset retirement obligations	253	200	500	474
(Gain) loss on sale of assets, net	(7)	(92)	(931)	(4,772)
TOTAL OPERATING EXPENSE	62,684	60,047	122,251	112,818
INCOME (LOSS) FROM OPERATIONS	57,840	(19,478)	122,855	(7,868)
OTHER INCOME (EXPENSE)
Interest and investment income	33	38	39	191
Interest expense	(3,981)	(1,443)	(7,488)	(2,491)
Other income (expense)	282	73	351	107
TOTAL OTHER EXPENSE	(3,666)	(1,332)	(7,098)	(2,193)
NET INCOME (LOSS)	54,174	(20,810)	115,757	(10,061)
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS	16	9	7	7
DISTRIBUTIONS ON REDEEMABLE PREFERRED UNITS	(672)	(1,310)	(1,786)	(3,114)
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS	53,518	(22,111)	113,978	(13,168)
ALLOCATION OF NET INCOME (LOSS):
General partner interest	0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO THE GENERAL PARTNER AND COMMON AND SUBORDINATED UNITS	53,518	(22,111)	113,978	(13,168)
Common Units
ALLOCATION OF NET INCOME (LOSS):
Allocation of net income (loss)	$ 32,100	$ (7,445)	$ 67,617	$ 862
NET INCOME (LOSS) ATTRIBUTABLE TO LIMITED PARTNERS PER COMMON AND SUBORDINATED UNIT:
Per unit (basic) (in dollars per share)	$ 0.33	$ (0.08)	$ 0.69	$ 0.01
Weighted average units outstanding (basic) (in shares)	97,990	96,356	97,448	96,418
Per unit (diluted) (in dollars per share)	$ 0.33	$ (0.08)	$ 0.69	$ 0.01
Weighted average units outstanding (diluted) (in shares)	97,990	96,418	97,448	96,481
DISTRIBUTIONS DECLARED AND PAID:
Per unit (in dollars per share)	$ 0.2875	$ 0.2625	$ 0.575	$ 0.525
Subordinated Units
ALLOCATION OF NET INCOME (LOSS):
Allocation of net income (loss)	$ 21,418	$ (14,666)	$ 46,361	$ (14,030)
NET INCOME (LOSS) ATTRIBUTABLE TO LIMITED PARTNERS PER COMMON AND SUBORDINATED UNIT:
Per unit (basic) (in dollars per share)	$ 0.22	$ (0.15)	$ 0.49	$ (0.15)
Weighted average units outstanding (basic) (in shares)	95,388	95,189	95,269	95,092
Per unit (diluted) (in dollars per share)	$ 0.22	$ (0.15)	$ 0.49	$ (0.15)
Weighted average units outstanding (diluted) (in shares)	95,388	95,092	95,269	95,092
DISTRIBUTIONS DECLARED AND PAID:
Per unit (in dollars per share)	$ 0.18375	$ 0.18375	$ 0.3675	$ 0.3675