Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash	$ 67,494	$ 16,066
Cash and Cash Equivalents, at Carrying Value	67,494	16,066
Accounts receivable, net	98,151	131,204
Fair value of derivatives	203,869	187,495
Prepaid expenses and other current assets	5,205	5,954
Total current assets	374,719	340,719
Properties and equipment, net	1,881,003	1,800,186
Assets held for sale - non-current	2,874	2,874
Fair value of derivatives	112,525	112,819
Other assets	83,979	83,990
Total Assets	2,455,100	2,340,588
Current liabilities:
Accounts payable	96,277	130,321
Production tax liability	21,541	21,314
Fair value of derivatives	404	570
Funds held for distribution	31,428	27,186
Accrued interest payable	20,170	9,109
Deferred income taxes	64,077	59,174
Other accrued expenses	15,826	62,717
Total current liabilities	249,723	310,391
Long-term debt	609,951	664,923
Deferred income taxes	129,323	125,693
Asset retirement obligation	72,148	71,992
Fair value of derivatives	212	197
Other liabilities	33,513	30,033
Total liabilities	1,094,870	1,203,229
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, 150,000,000 authorized, 40,022,529 and 35,927,985 issued as of March 31, 2015 and December 31, 2014, respectively	400	359
Additional paid-in capital	895,257	689,209
Retained earnings	465,764	448,702
Treasury shares - at cost, 26,811 and 21,643 as of March 31, 2015 and December 31, 2014, respectively	(1,191)	(911)
Total shareholders' equity	1,360,230	1,137,359
Total Liabilities and Shareholders' Equity	$ 2,455,100	$ 2,340,588