Guarantor Financial Statements - Cash Flow Statement (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		$ 416,501	$ 356,389	$ 155,777
Cash flows from investing activities:
Additions to oil and natural gas properties		(419,512)	(498,339)	(292,586)
Acquisition of leasehold interests		(437,455)	(845,826)	(195,893)
Acquisition of royalty interests		(43,907)	(57,689)	(444,083)
Purchase of other property and equipment		(1,213)	(44,213)	(2,234)
Proceeds from sale of assets		9,739	56	72
Equity investments	$ (600)	(2,702)	(34,477)	0
Intercompany transfers		0	0	0
Other investing activities		0	(1,453)	(7,578)
Net cash used in investing activities		(895,050)	(1,481,997)	(940,140)
Cash flows from financing activities:
Proceeds from borrowings on credit facility		425,001	509,400	59,000
Repayment on credit facility		(603,001)	(295,900)	(49,000)
Debit issuance costs		(526)	(3,469)	(12,361)
Public offering costs		(586)	(2,994)	(1,009)
Proceeds from senior notes		0	0	450,000
Proceeds from public offerings		650,688	928,432	322,680
Distribution to parent		0	0
Distribution from subsidiary		0	0
Exercise of stock options		4,873	7,081	3,501
Distribution to non-controlling interest		(7,968)	(2,314)	0
Intercompany transfers		0	0	0
Other financing activities			618	(9,120)
Net cash provided by financing activities		468,481	1,140,236	773,560
Net increase (decrease) in cash and cash equivalents		(10,068)	14,628	(10,803)
Cash and cash equivalents at beginning of period		30,183	15,555	26,358
Cash and cash equivalents at end of period		20,115	30,183	15,555
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		0	0	0
Cash flows from investing activities:
Additions to oil and natural gas properties		0	0	0
Acquisition of leasehold interests		0	0	0
Acquisition of royalty interests		0	0	0
Purchase of other property and equipment		0	0
Proceeds from sale of assets		0
Equity investments		0	0
Intercompany transfers		0	0	0
Other investing activities		0	0	0
Net cash used in investing activities		0	0	0
Cash flows from financing activities:
Proceeds from borrowings on credit facility		0	0	0
Repayment on credit facility		0	0	0
Debit issuance costs		0
Public offering costs		0
Proceeds from senior notes				0
Proceeds from public offerings		0	0	0
Distribution to parent		0	148,760
Distribution from subsidiary		(60,587)	(166,372)
Exercise of stock options		0
Distribution to non-controlling interest		60,587	17,612
Intercompany transfers		0	0	0
Other financing activities			0	0
Net cash provided by financing activities		0	0	0
Net increase (decrease) in cash and cash equivalents		0	0	0
Cash and cash equivalents at beginning of period		0	0	0
Cash and cash equivalents at end of period		0	0	0
Parent Company [Member] | Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		(37,597)	(8,862)	12,302
Cash flows from investing activities:
Additions to oil and natural gas properties		0	0	0
Acquisition of leasehold interests		0	0	0
Acquisition of royalty interests		0	0	0
Purchase of other property and equipment		0	0
Proceeds from sale of assets		0
Equity investments		0	0
Intercompany transfers		(145,023)	(642,978)	(289,344)
Other investing activities		0	0	0
Net cash used in investing activities		(145,023)	(642,978)	(289,344)
Cash flows from financing activities:
Proceeds from borrowings on credit facility		0	0	0
Repayment on credit facility		0	0	0
Debit issuance costs		0
Public offering costs		(586)
Proceeds from senior notes				10,000
Proceeds from public offerings		650,688	693,886	322,680
Distribution to parent		0	0
Distribution from subsidiary		60,587	166,372
Exercise of stock options		4,873
Distribution to non-controlling interest		0	0
Intercompany transfers		(532,800)	(217,900)	(49,000)
Other financing activities			8,962	(6,126)
Net cash provided by financing activities		182,762	651,320	277,554
Net increase (decrease) in cash and cash equivalents		142	(520)	512
Cash and cash equivalents at beginning of period		6	526	14
Cash and cash equivalents at end of period		148	6	526
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		390,266	313,438	138,630
Cash flows from investing activities:
Additions to oil and natural gas properties		(419,512)	(493,063)	(292,586)
Acquisition of leasehold interests		(437,455)	(845,826)	(195,893)
Acquisition of royalty interests		0	0	0
Purchase of other property and equipment		(1,213)	(44,213)
Proceeds from sale of assets		9,739
Equity investments		(2,702)	(627)
Intercompany transfers		145,023	642,978	289,344
Other investing activities		0	(1,453)	(7,578)
Net cash used in investing activities		(706,120)	(742,204)	(206,713)
Cash flows from financing activities:
Proceeds from borrowings on credit facility		390,501	431,400	59,000
Repayment on credit facility		(603,001)	(217,900)	(49,000)
Debit issuance costs		(85)
Public offering costs		0
Proceeds from senior notes				0
Proceeds from public offerings		0	0	0
Distribution to parent		0	0
Distribution from subsidiary		0	0
Exercise of stock options		0
Distribution to non-controlling interest		0	0
Intercompany transfers		532,800	217,900	49,000
Other financing activities			(1,834)	(2,994)
Net cash provided by financing activities		320,215	429,566	56,006
Net increase (decrease) in cash and cash equivalents		4,361	800	(12,077)
Cash and cash equivalents at beginning of period		15,067	14,267	26,344
Cash and cash equivalents at end of period		19,428	15,067	14,267
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		63,832	51,813	4,845
Cash flows from investing activities:
Additions to oil and natural gas properties		0	(5,276)	0
Acquisition of leasehold interests		0	0	0
Acquisition of royalty interests		(43,907)	(57,689)	(444,083)
Purchase of other property and equipment		0	0
Proceeds from sale of assets		0
Equity investments		0	(33,850)
Intercompany transfers		0	0	0
Other investing activities		0	0	0
Net cash used in investing activities		(43,907)	(96,815)	(444,083)
Cash flows from financing activities:
Proceeds from borrowings on credit facility		34,500	78,000	0
Repayment on credit facility		0	(78,000)	0
Debit issuance costs		(441)
Public offering costs		0
Proceeds from senior notes				440,000
Proceeds from public offerings		0	234,546	0
Distribution to parent		0	(148,760)
Distribution from subsidiary		0	0
Exercise of stock options		0
Distribution to non-controlling interest		(68,555)	(19,926)
Intercompany transfers		0	0	0
Other financing activities			(6,510)	0
Net cash provided by financing activities		(34,496)	59,350	440,000
Net increase (decrease) in cash and cash equivalents		(14,571)	14,348	762
Cash and cash equivalents at beginning of period		15,110	762	0
Cash and cash equivalents at end of period		$ 539	$ 15,110	$ 762