Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 45,878	$ 50,483
Restricted cash	15,221	20,570
Accounts receivable, net:
Oil and natural gas	127,193	128,352
Joint interest	49,913	70,759
Other	6,011	18,022
Derivative financial instruments	2,330	8,226
Inventory and other	12,047	9,442
Total current assets	258,593	305,854
Equity investments	56,514	57,562
Oil and natural gas properties (full cost accounting method):
Unproved oil and natural gas properties and development costs not being amortized	369,000	425,307
Proved developed and undeveloped oil and natural gas properties	3,736,988	3,554,210
Accumulated depletion	(2,316,974)	(2,183,464)
Oil and natural gas properties, net	1,789,014	1,796,053
Gathering assets	36,699	33,473
Accumulated depreciation and amortization	(11,184)	(10,338)
Gathering assets, net	25,515	23,135
Office, field and other equipment, net	25,873	27,204
Deferred financing costs, net	35,011	28,807
Derivative financial instruments	2,773	6,829
Goodwill	163,155	163,155
Other assets	30	29
Total assets	2,356,478	2,408,628
Current liabilities:
Accounts payable and accrued liabilities	106,787	109,217
Revenues and royalties payable	184,025	154,862
Drilling advances	51,589	22,971
Accrued interest payable	26,284	18,144
Current portion of asset retirement obligations	191	191
Income taxes payable	0	0
Derivative financial instruments	29,451	11,919
Current maturities of long-term debt	0	31,866
Total current liabilities	398,327	349,170
Long-term debt	1,511,647	1,858,912
Deferred income taxes	0	0
Derivative financial instruments	5,454	9,671
Asset retirement obligations and other long-term liabilities	44,468	42,970
Commitments and contingencies	0	0
Shareholders’ equity:
Common stock, $0.001 par value; 350,000,000 authorized shares; 273,277,566 shares issued and 272,738,345 shares outstanding at June 30, 2014; 218,783,540 shares issued and 218,244,319 shares outstanding at December 31, 2013	270	215
Subscription rights, $0.001 par value; none issued and outstanding at June 30, 2014; 54,574,734 issued and outstanding at December 31, 2013	0	55
Additional paid-in capital	3,497,849	3,219,748
Accumulated deficit	(3,094,058)	(3,064,634)
Treasury stock, at cost; 539,221 shares at June 30, 2014 and December 31, 2013	(7,479)	(7,479)
Total shareholders' equity	396,582	147,905
Total liabilities and shareholders' equity	$ 2,356,478	$ 2,408,628