Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 1,052	$ 18,593
Accounts receivable, net of allowance for doubtful accounts of $1,972 and $5,342 at March 31, 2014 and December 31, 2013, respectively	187,872	139,788
Materials and supplies	8,217	10,998
Current derivative asset (Note 9)	0	515
Current deferred tax asset	13,585	13,585
Assets held for sale	0	15,621
Prepaid expenses and other	12,537	12,931
Total current assets	223,263	212,031
Oil and natural gas properties on the full cost method:
Proved properties	4,353,248	4,235,712
Unproved properties not being amortized	557,149	545,588
Drilling equipment	1,482,902	1,477,093
Gas gathering and processing equipment	556,448	549,422
Transportation equipment	40,125	39,666
Other	95,537	87,435
Property, plant and equipment, gross, total	7,085,409	6,934,916
Less accumulated depreciation, depletion, amortization, and impairment	3,279,509	3,212,225
Net property and equipment	3,805,900	3,722,691
Debt issuance cost	11,447	11,844
Goodwill	62,808	62,808
Other assets	13,418	13,016
Total assets	4,116,836	4,022,390
Current liabilities:
Accounts payable	160,990	154,062
Accrued liabilities (Note 4)	65,225	64,363
Income taxes payable	10,853	7,474
Current derivative liabilities (Note 9)	14,540	5,561
Current portion of other long-term liabilities (Note 5)	11,629	12,113
Total current liabilities	263,237	243,573
Long-term debt (Note 5)	645,809	645,696
Other long-term liabilities (Note 5)	145,454	158,331
Deferred income taxes	827,554	801,398
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0	0
Common stock, $.20 par value, 175,000,000 shares authorized, 49,575,959 and 49,107,004 shares issued, respectively	9,725	9,659
Capital in excess of par value	449,849	445,470
Retained earnings	1,775,208	1,718,263
Total shareholders' equity	2,234,782	2,173,392
Total liabilities and shareholders' equity	$ 4,116,836	$ 4,022,390