Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement [Abstract]
OIL AND GAS REVENUES	$ 368,180	$ 202,167	$ 138,123
COSTS AND EXPENSES
Lease operating	31,471	28,314	23,659
Production tax	13,542	5,697	3,648
Ad valorem tax	9,813	3,625	3,707
Depreciation, depletion and amortization	165,621	84,606	47,030
General and administrative (inclusive of stock-based compensation expense of $11,689, 11,864 and $16,608 for the years ended December 31, 2012, 2011 and 2010, respectively)	48,708	41,539	35,906
Accretion related to asset retirement obligations	372	235	216
TOTAL COSTS AND EXPENSES	269,527	164,016	114,166
OPERATING INCOME	98,653	38,151	23,957
OTHER INCOME AND EXPENSES
Gain (loss) on derivative instruments, net	31,371	48,423	47,782
Loss on extinguishment of debt	0	(897)	(31,023)
Interest expense	(73,006)	(50,998)	(43,264)
Capitalized interest	24,848	23,369	20,746
Other income (expense), net	267	97	212
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	82,133	58,145	18,410
INCOME TAX EXPENSE	(30,956)	(25,611)	(6,685)
NET INCOME FROM CONTINUING OPERATIONS	51,177	32,534	11,725
NET INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	4,310	4,095	(1,775)
NET INCOME	$ 55,487	$ 36,629	$ 9,950
NET INCOME PER COMMON SHARE - BASIC
Net income from continued operations (in dollars per share)	$ 1.29	$ 0.83	$ 0.34
Net income (loss) from discontinued operations (in dollars per share)	$ 0.11	$ 0.11	$ (0.05)
Net income per share basic (in dollars per share)	$ 1.40	$ 0.94	$ 0.29
NET INCOME PER COMMON SHARE - DILUTED
Net income from continuing operations (in dollars per share)	$ 1.28	$ 0.82	$ 0.34
Net income (loss) from discontinued operations (in dollars per share)	$ 0.11	$ 0.10	$ (0.05)
Net income per share, diluted (in dollars per share)	$ 1.39	$ 0.92	$ 0.29
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)	39,591	39,077	33,861
Diluted (in shares)	40,026	39,668	34,305