Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net (loss) income	$ (207,213)	$ 34,589
Adjustments to reconcile net (loss) income to net cash provided by operating activities
Unrealized loss on derivatives	32,090	8,342
Depletion, depreciation and amortization	98,239	55,827
Accretion of asset retirement obligations	244	241
Full-cost ceiling impairment	296,153	0
Stock-based compensation expense	5,131	3,629
Deferred income tax (benefit) provision	(115,740)	17,356
Net loss on asset sales and inventory impairment	97	0
Changes in operating assets and liabilities
Accounts receivable	(12,161)	(13,338)
Lease and well equipment inventory	(269)	(36)
Prepaid expenses	(1,143)	(656)
Other assets	446	(468)
Accounts payable, accrued liabilities and other current liabilities	13,316	(517)
Royalties payable	4,253	5,890
Advances from joint interest owners	447	0
Income taxes payable	(444)	2,814
Other long-term liabilities	(56)	(198)
Net cash provided by operating activities	113,390	113,475
Investing activities
Oil and natural gas properties capital expenditures	(237,027)	(234,335)
Expenditures for other property and equipment	(32,885)	(1,884)
Business combination, net of cash acquired	(23,671)	0
Restricted cash in less than wholly-owned subsidiaries	(413)	0
Net cash used in investing activities	(293,996)	(236,219)
Financing activities
Repayments of borrowings	(476,982)	(180,000)
Borrowings under Credit Agreement	125,000	130,000
Proceeds from issuance of senior unsecured notes	400,000	0
Cost to issue senior unsecured notes	(8,789)	0
Proceeds from issuance of common stock	188,720	181,875
Cost to issue equity	(1,172)	(504)
Proceeds from stock options exercised	10	6
Capital commitment from non-controlling interest in subsidiary	600	0
Taxes paid related to net share settlement of stock-based compensation	(1,565)	(285)
Net cash provided by financing activities	225,822	131,092
Increase in cash	45,216	8,348
Cash at beginning of period	8,407	6,287
Cash at end of period	$ 53,623	$ 14,635