Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 1,195	$ 835
Accounts receivable, net of allowance for doubtful accounts of $5,343 both at March 31, 2012 and at December 31, 2011	166,031	165,276
Materials and supplies	7,785	8,202
Current derivative asset (Note 9)	26,592	31,938
Current deferred tax asset	10,936	10,936
Prepaid expenses and other	11,578	11,278
Total current assets	224,117	228,465
Property and equipment:
Drilling equipment	1,448,635	1,423,570
Oil and natural gas properties on the full cost method:
Proved properties	3,400,158	3,302,032
Undeveloped leasehold not being amortized	189,183	185,632
Gas gathering and processing equipment	303,477	278,919
Transportation equipment	35,320	34,118
Other	40,942	37,544
Property, plant and equipment, gross, total	5,417,715	5,261,815
Less accumulated depreciation, depletion, amortization and impairment	2,395,021	2,319,484
Net property and equipment	3,022,694	2,942,331
Deferred offering costs	5,520	5,671
Goodwill	62,808	62,808
Other intangible assets, net	1,542	1,855
Non-current derivative asset (Note 9)	384	4,514
Other assets	10,992	11,076
Total assets	3,328,057	3,256,720
Current liabilities:
Accounts payable	120,842	143,311
Accrued liabilities (Note 4)	47,473	51,733
Income taxes payable	1,415	781
Contract advances	2,059	2,055
Current portion of derivative liabilities (Note 9)	2,775	2,657
Current portion of other long-term liabilities (Note 5)	11,691	12,213
Total current liabilities	186,255	212,750
Long-term debt (Note 5)	315,800	300,000
Non-current derivative liabilities (Note 9)	1,359	0
Other long-term liabilities (Note 5)	110,687	113,830
Deferred income taxes	714,877	683,123
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, 48,572,214 and 48,151,442 shares issued, respectively	9,560	9,541
Capital in excess of par value	413,236	408,109
Accumulated other comprehensive loss	13,503	19,026
Retained earnings	1,562,780	1,510,341
Total shareholders' equity	1,999,079	1,947,017
Total liabilities and shareholders' equity	$ 3,328,057	$ 3,256,720