Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 1,085	$ 835
Accounts receivable, net of allowance for doubtful accounts of $5,343 both at June 30, 2012 and at December 31, 2011	161,496	165,276
Materials and supplies	8,331	8,202
Current derivative asset (Note 9)	42,846	31,938
Current deferred tax asset	10,936	10,936
Prepaid expenses and other	12,177	11,278
Total current assets	236,871	228,465
Property and equipment:
Drilling equipment	1,467,071	1,423,570
Oil and natural gas properties on the full cost method:
Proved properties	3,525,177	3,302,032
Undeveloped leasehold not being amortized	208,694	185,632
Gas gathering and processing equipment	337,063	278,919
Transportation equipment	36,620	34,118
Other	44,113	37,544
Property, plant and equipment, gross, total	5,618,738	5,261,815
Less accumulated depreciation, depletion, amortization and impairment	2,593,153	2,319,484
Net property and equipment	3,025,585	2,942,331
Deferred offering costs	5,375	5,671
Goodwill	62,808	62,808
Other intangible assets, net	1,228	1,855
Non-current derivative asset (Note 9)	9,507	4,514
Other assets	12,063	11,076
Total assets	3,353,437	3,256,720
Current liabilities:
Accounts payable	127,794	143,311
Accrued liabilities (Note 4)	55,059	51,733
Income taxes payable	0	781
Contract advances	897	2,055
Current portion of derivative liabilities (Note 9)	0	2,657
Current portion of other long-term liabilities (Note 5)	11,583	12,213
Total current liabilities	195,333	212,750
Long-term debt (Note 5)	332,900	300,000
Non-current derivative liabilities (Note 9)	635	0
Other long-term liabilities (Note 5)	115,727	113,830
Deferred income taxes	708,464	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, 48,589,289 and 48,151,442 shares issued, respectively	9,581	9,541
Capital in excess of par value	417,005	408,109
Accumulated other comprehensive income	30,314	19,026
Retained earnings	1,543,478	1,510,341
Total shareholders' equity	2,000,378	1,947,017
Total liabilities and shareholders' equity	$ 3,353,437	$ 3,256,720