Condensed Consolidated Statements of Cash Flows - Unaudited - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Cash Flows [Abstract]
Current period net income	$ 64,924	$ 45,900
Adjustments to reconcile net income to net cash provided by operating activities
Unrealized gain on derivatives	(10,416)	(20,631)
Depletion, depreciation and amortization	55,369	33,992
Accretion of asset retirement obligations	364	300
Stock-based compensation expense	4,179	4,166
Amortization of debt issuance cost	365	44
Net gain on asset sales and inventory impairment	0	(7)
Changes in operating assets and liabilities
Accounts receivable	3,268	(16,777)
Lease and well equipment inventory	(3,806)	147
Prepaid expenses	(674)	(2,251)
Other assets	(249)	39
Accounts payable, accrued liabilities and other current liabilities	15,184	8,256
Royalties payable	1,627	6,984
Advances from joint interest owners	6,063	1,255
Other long-term liabilities	(49)	(108)
Net cash provided by operating activities	136,149	61,309
Investing activities
Oil and natural gas properties capital expenditures	(183,422)	(204,457)
Expenditures for midstream and other property and equipment	(37,332)	(20,867)
Proceeds from sale of assets	0	350
Net cash used in investing activities	(220,754)	(224,974)
Financing activities
Proceeds from stock options exercised	164	1,981
Contributions related to formation of Joint Venture	14,700	171,500
Contributions from non-controlling interest owners of less-than-wholly-owned subsidiaries	29,400	4,900
Distributions to non-controlling interest owners of less-than-wholly-owned subsidiaries	(4,900)	0
Taxes paid related to net share settlement of stock-based compensation	(4,458)	(1,896)
Purchase of non-controlling interest of less-than-wholly-owned subsidiary	0	(2,653)
Net cash provided by financing activities	34,906	173,832
(Decrease) increase in cash and restricted cash	(49,699)	10,167
Cash and restricted cash at beginning of period	102,482	214,142
Cash and restricted cash at end of period	$ 52,783	$ 224,309