CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 12,285	$ 18,878
Accounts receivable:
Oil and gas sales	61,650	35,618
Joint interest billing	20,901	10,815
Other	1,519	3,866
Commodity derivative contracts	9,006	5,695
Deferred income taxes	11,517	6,027
Other current assets	10,720	8,573
Total current assets	127,598	89,472
PROPERTY AND EQUIPMENT:
Oil and gas properties, on the basis of full-cost accounting	2,744,032	1,836,664
Other property and equipment	7,907	5,038
Less accumulated depreciation, depletion, and amortization	(369,099)	(274,294)
Net property and equipment	2,382,840	1,567,408
OTHER ASSETS:
Commodity derivative contracts	4,631	1,717
Other noncurrent assets	50,775	25,413
Total other assets	55,406	27,130
TOTAL	2,565,844	1,684,010
CURRENT LIABILITIES:
Accounts payable	22,438	29,196
Accrued liabilities	150,984	98,649
Commodity derivative contracts	8,883	7,582
Total current liabilities	182,305	135,427
LONG-TERM LIABILITIES:
Asset retirement obligations	22,617	15,245
Commodity derivative contracts	495	3,943
Long-term debt	1,521,150	694,000
Deferred income taxes	196,115	190,625
Other long-term liabilities	1,088	1,189
Total long-term liabilities	1,741,465	905,002
COMMITMENTS AND CONTINGENCIES (Note 11)
STOCKHOLDERS' EQUITY
Preferred stock
Common stock, $0.01 par value, 300,000,000 shares authorized; 68,652,983 shares issued and 68,545,925 outstanding at June 30, 2013 and 66,619,711 shares issued and outstanding at December 31, 2012	686	666
Treasury stock	(605)
Additional paid-in-capital	833,692	830,003
Retained deficit/accumulated loss	(191,702)	(187,091)
Total stockholders' equity	642,074	643,581
TOTAL	2,565,844	1,684,010
Series A mandatorily convertible preferred stock, $0.01 par value, $338,000 and $325,000 liquidation value, respectively; 8% cumulative dividends; 325,000 shares issued and outstanding
STOCKHOLDERS' EQUITY
Preferred stock	$ 3	$ 3