Consolidated Balance Sheets (Audited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 43,212	$ 2,457
Restricted cash	3,949	3,942
Accounts receivable, net	73,947	64,880
Accounts receivable affiliates	14,814	4,842
Fair value of derivatives	16,287	52,042
Deferred income taxes	17,045	36,151
Prepaid expenses and other current assets	7,993	7,635
Total current assets	177,247	171,949
Properties and equipment, net	1,438,880	1,616,706
Assets held for sale	32,160	0
Fair value of derivatives	10,421	6,883
Other assets	32,727	31,310
Total Assets	1,691,435	1,826,848
Current liabilities:
Accounts payable	75,520	82,716
Accounts payable affiliates	821	5,296
Production tax liability	25,228	25,899
Fair value of derivatives	5,702	18,439
Funds held for distribution	27,730	34,228
Accrued interest payable	8,825	11,056
Other accrued expenses	23,976	25,715
Total current liabilities	167,802	203,349
Long-term debt	639,127	676,579
Deferred income taxes	118,246	148,427
Asset retirement obligation	35,367	61,563
Fair value of derivatives	4,475	10,137
Liabilities held for sale	22,370	0
Other liabilities	15,920	23,612
Total liabilities	1,003,307	1,123,667
Commitments and contingent liabilities
Shareholders' Equity:
Preferred shares - par value $0.01 per share, 50,000,000 shares authorized,none issued	0	0
Common shares - par value $0.01 per share, 100,000,000 authorized, 30,443,287 and 30,294,224 issued as of June 30, 2013 and December 31, 2012, respectively	304	303
Additional paid-in capital	392,617	387,494
Retained earnings	296,068	315,568
Treasury shares - at cost, 18,141 and 5,059 as of June 30, 2013 and December 31, 2012, respectively	(861)	(184)
Total shareholders' equity	688,128	703,181
Total Liabilities and Shareholders' Equity	$ 1,691,435	$ 1,826,848