Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net (loss) income	$ (29,720)	$ 12,073
Adjustments to reconcile net (loss) income to net cash provided by operating activities
Unrealized loss on derivatives	6,626	1,149
Depletion, depreciation and amortization	74,593	52,799
Accretion of asset retirement obligations	248	170
Full-cost ceiling impairment	21,229	36,801
Stock-based compensation expense	(2,763)	223
Deferred income tax provision	1,661	(1,430)
Net loss on asset sales and inventory impairment	192	60
Changes in operating assets and liabilities
Accounts receivable	(886)	(8,718)
Lease and well equipment inventory	198	(285)
Prepaid expenses	(2,148)	179
Other assets	(728)	(650)
Accounts payable, accrued liabilities and other current liabilities	(10,702)	6,105
Royalties payable	(3,812)	(4,065)
Advances from joint interest owners	(1,505)	1,782
Income taxes payable	980	188
Other long-term liabilities	1,139	406
Net cash provided by operating activities	127,192	80,325
Investing activities
Oil and natural gas properties capital expenditures	(257,216)	(212,702)
Expenditures for other property and equipment	(3,058)	(5,297)
Purchases of certificates of deposit	(61)	(416)
Maturities of certificates of deposit	251	1,485
Net cash used in investing activities	(260,084)	(216,930)
Financing activities
Repayments of borrowings under Credit Agreement	(130,000)	(123,000)
Borrowings under Credit Agreement	125,000	116,000
Proceeds from issuance of common stock	149,069	146,510
Swing Sale Profit	0	24
Cost to issue equity	(6,933)	(11,599)
Proceeds from stock options exercised	0	2,660
Taxes paid related to net share settlement of stock-based compensation	(9)	0
Payment of dividends - Class B	0	(96)
Net cash provided by financing activities	137,127	130,499
Increase (decrease) in cash	4,235	(6,106)
Cash at beginning of period	2,095	10,284
Cash at end of period	$ 6,330	$ 4,178