Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net (loss) income	$ (679,524)	$ 110,754	$ 45,094
Adjustments to reconcile net (loss) income to net cash provided by operating activities
Unrealized loss (gain) on derivatives	39,265	(58,302)	7,232
Depletion, depreciation and amortization	178,847	134,737	98,395
Accretion of asset retirement obligations	734	504	348
Full-cost ceiling impairment	801,166	0	21,229
Stock-based compensation expense	9,450	5,524	3,897
Deferred income tax (benefit) provision	(150,327)	64,242	9,293
Amortization of debt issuance costs and discounts	852	0	0
Net (gain) loss on asset sales and inventory impairment	(908)	0	192
Changes in operating assets and liabilities
Accounts receivable	3,633	(13,318)	(2,160)
Lease and well equipment inventory	(180)	(211)	243
Prepaid expenses	(544)	(783)	(668)
Other assets	(552)	1,212	(548)
Accounts payable, accrued liabilities and other current liabilities	1,375	607	(3,638)
Royalties payable	1,654	6,663	1,257
Advances from joint interest owners	700	0	(1,515)
Income taxes payable	2,405	39	404
Other long-term liabilities	489	(187)	415
Net cash provided by operating activities	208,535	251,481	179,470
Investing activities
Proceeds from sale of assets	139,836	79	0
Oil and natural gas properties capital expenditures	(432,715)	(560,849)	(363,192)
Expenditures for other property and equipment	(64,499)	(9,152)	(3,977)
Business combination, net of cash acquired	(24,028)	0	0
Maturities of certificates of deposit, net of purchases	0	0	230
Restricted cash	(43,098)	0	0
Restricted cash in less-than-wholly-owned subsidiaries	(650)	(609)	0
Net cash used in investing activities	(425,154)	(570,531)	(366,939)
Financing activities
Repayments of borrowings	(476,982)	(180,000)	(130,000)
Borrowings under Credit Agreement	125,000	320,000	180,000
Proceeds from issuance of common stock	188,720	181,875	149,069
Swing sale profit contribution	400,000	0	0
Cost to issue equity	(1,158)	(590)	(7,390)
Cost to issue senior unsecured notes	(9,598)	0	0
Proceeds from stock options exercised	10	43	0
Capital contribution from non-controlling interest owners in less-than-wholly-owned subsidiaries	562	150	0
Taxes paid related to net share settlement of stock-based compensation	(1,610)	(308)	(18)
Net cash provided by financing activities	224,944	321,170	191,661
Increase in cash	8,325	2,120	4,192
Cash at beginning of year	8,407	6,287	2,095
Cash at end of year	$ 16,732	$ 8,407	$ 6,287