Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 835	$ 1,049
Accounts receivable (less allowance for doubtful accounts of $5,199 and $5,039 at December 31, 2015 and 2014, respectively)	79,941	189,812
Materials and supplies	3,565	5,590
Current derivative asset (Note 12)	10,186	31,139
Current income tax receivable	21,002	0
Current deferred tax asset (Note 8)	14,206	11,527
Assets held for sale (Note 2)	615	0
Prepaid expenses and other	9,908	13,374
Total current assets	140,258	252,491
Oil and natural gas properties, on the full cost method:
Proved properties	5,401,618	4,990,753
Unproved properties not being amortized	337,099	485,568
Drilling equipment	1,567,560	1,620,692
Gas gathering and processing equipment	689,063	628,689
Saltwater disposal systems	60,316	56,702
Corporate land and building	49,890	16,104
Transportation equipment	40,072	40,693
Other	45,489	41,602
Property, plant and equipment, gross, total	8,191,107	7,880,803
Less accumulated depreciation, depletion, amortization, and impairment	5,609,980	3,747,412
Net property and equipment	2,581,127	4,133,391
Debt issuance cost	8,667	10,255
Goodwill (Note 2)	62,808	62,808
Non-current derivative asset (Note 12)	968	0
Other assets	14,681	14,783
Total assets	2,808,509	4,473,728
Current liabilities:
Accounts payable	87,413	218,500
Accrued liabilities (Note 5)	46,918	70,171
Income taxes payable	0	481
Current portion of other long-term liabilities (Note 6)	16,560	15,019
Total current liabilities	150,891	304,171
Long-term debt (Note 6)	927,662	812,163
Non-current derivative liabilities (Note 12)	285	0
Other long-term liabilities (Note 6)	140,341	148,785
Deferred income taxes (Note 8)	275,750	876,215
Commitments and contingencies (Note 15)	0	0
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0	0
Common stock, $0.20 par value, 175,000,000 shares authorized, 50,413,101 and 49,593,812 shares issued as of December 31, 2015 and 2014, respectively	9,831	9,732
Capital in excess of par value	486,571	468,123
Retained earnings	817,178	1,854,539
Total shareholders' equity	1,313,580	2,332,394
Total liabilities and shareholders' equity	$ 2,808,509	$ 4,473,728