Consolidated Balance Sheet (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 91,901	$ 213,447
Short-term investments	0	25,891
Accounts receivable — oil and gas revenues	175,653	110,341
Accounts receivable — joint interest partners	139,459	99,194
Inventory	20,652	20,707
Prepaid expenses	10,191	1,770
Advances to joint interest partners	760	1,985
Derivative instruments	2,264	19,016
Deferred income taxes	6,335	0
Other current assets	391	335
Total current assets	447,606	492,686
Property, plant and equipment
Oil and gas properties (successful efforts method)	4,528,958	2,348,128
Other property and equipment	188,468	49,732
Less: accumulated depreciation, depletion, amortization and impairment	(637,676)	(391,260)
Total property, plant and equipment, net	4,079,750	2,006,600
Assets held for sale	137,066	0
Derivative instruments	1,333	4,981
Deferred costs and other assets	46,169	24,527
Total assets	4,711,924	2,528,794
Current liabilities
Accounts payable	8,920	12,491
Advances from joint interest partners	12,829	21,176
Revenues and production taxes payable	146,741	71,553
Accrued liabilities	241,830	189,863
Accrued interest payable	47,910	30,096
Derivative instruments	8,188	1,048
Deferred income taxes	0	4,558
Total current liabilities	466,418	330,785
Long-term debt	2,535,570	1,200,000
Asset retirement obligations	35,918	22,956
Derivative instruments	139	380
Deferred income taxes	323,147	177,671
Other liabilities	2,183	1,997
Total liabilities	3,363,375	1,733,789
Commitments and contingencies (Note 17)
Stockholders’ equity
Common stock, $0.01 par value; 300,000,000 shares authorized; 100,866,589 shares and 93,432,712 shares issued at December 31, 2013 and 2012, respectively	996	925
Treasury stock, at cost; 167,155 shares and 129,414 shares at December 31, 2013 and 2012, respectively	(5,362)	(3,796)
Additional paid-in-capital	985,023	657,943
Retained earnings	367,892	139,933
Total stockholders’ equity	1,348,549	795,005
Total liabilities and stockholders’ equity	$ 4,711,924	$ 2,528,794