Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 835	$ 1,359
Accounts receivable (less allowance for doubtful accounts of $5,343 and $5,083)	165,276	130,142
Materials and supplies	8,202	6,316
Current derivative asset (Note 13)	31,938	5,568
Current income tax receivable	0	25,211
Current deferred tax asset (Note 8)	10,936	13,537
Prepaid expenses and other	11,278	6,047
Total current assets	228,465	188,180
Property and equipment:
Drilling equipment	1,423,570	1,273,861
Oil and natural gas properties, on the full cost method:
Proved properties	3,302,032	2,738,093
Undeveloped leasehold not being amortized	185,632	175,065
Gas gathering and processing equipment	278,919	199,564
Transportation equipment	34,118	31,688
Other	37,544	28,511
Property, plant and equipment, gross, total	5,261,815	4,446,782
Less accumulated depreciation, depletion, amortization and impairment	2,319,484	2,047,031
Net property and equipment	2,942,331	2,399,751
Deferred offering costs	5,671	0
Goodwill (Note 2)	62,808	62,808
Other intangible assets, net	1,855	3,022
Non-current derivative asset (Note 13)	4,514	2,537
Other assets	11,076	12,942
Total assets	3,256,720	2,669,240
Current liabilities:
Accounts payable	143,311	89,885
Accrued liabilities (Note 5)	51,733	30,093
Income taxes payable	781	0
Contract advances	2,055	2,582
Current portion of derivative liabilities (Note 13)	2,657	14,446
Current portion of other long-term liabilities (Note 6)	12,213	10,122
Total current liabilities	212,750	147,128
Long-term debt (Note 6)	300,000	163,000
Non-current derivative liabilities (Note 13)	0	4,359
Other long-term liabilities (Note 6)	113,830	88,030
Deferred income taxes (Note 8)	683,123	556,106
Commitments and contingencies (Note 15)
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, 48,151,442 and 47,910,431 shares issued as of December 31, 2011 and 2010, respectively	9,541	9,493
Capital in excess of par value	408,109	393,501
Accumulated other comprehensive income (loss) (net of tax of $11,961 and ($4,243), respectively)	19,026	(6,851)
Retained earnings	1,510,341	1,314,474
Total shareholders' equity	1,947,017	1,710,617
Total liabilities and shareholders' equity	$ 3,256,720	$ 2,669,240