CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 12,013	$ 9,070
Adjustments to reconcile net income to net cash provided by operating activities:
Accretion of discount on available-for-sale debt securities	(30)	(29)
Amortization of deferred offering costs	106	102
Depreciation, depletion and amortization	23,381	21,337
Change in fair value of derivative financial instruments	(2,156)	(1,642)
Gain on sale of US treasury bonds - available for sale		(4)
Stock option expense	945	848
Deferred tax expense (benefit)	39	(11)
Change in assets and liabilities:
Decrease (increase) in accounts receivable-trade	(1,489)	726
Increase in other assets	(869)	(43)
Increase in accounts payable and accruals	1,666	2,713
Decrease in other long-term liabilities	(1,194)	(858)
Net cash provided by operating activities	32,412	32,209
Cash flows from investing activities:
Purchase, exploration and development of oil and gas properties	(22,113)	(43,920)
Purchase of property and equipment	(1,766)	(731)
Proceeds from US treasury bonds - available for sale		13
Net cash used in investing activities	(23,879)	(44,638)
Cash flows from financing activities:
Proceeds from line of credit		10,000
Payments on debt and debentures	(10,017)	(91)
Proceeds from the exercise of stock options	361
Issuance of common stock, net		37
Net cash provided by (used in) financing activities	(9,656)	9,946
Net decrease in cash and cash equivalents	(1,123)	(2,483)
Cash and cash equivalents at beginning of period	8,475	10,614
Cash and cash equivalents at end of period	7,352	8,131
Supplemental disclosure of cash flow information
Cash paid for interest, net of amounts capitalized	1,347	1,632
Noncash investing and financing activities
Accrued preferred stock dividend	$ 5	$ 5