Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 248		$ 170
Accounts receivable	73,209		67,318
Deferred tax asset	2,757		5,679
Other current assets	8,085		7,370
Total Current Assets	84,299		80,537
Property and Equipment:
Property and Equipment	5,337,272		5,192,793
Less - Accumulated depreciation, depletion, and amortization	(2,908,302)		(2,847,773)
Property and Equipment, Net	2,428,970		2,345,020
Other Long-Term Assets	17,930		18,504
Total Assets	2,531,199		2,444,061
Current Liabilities:
Accounts payable and accrued liabilities	69,656		75,378
Accrued capital costs	90,042		73,190
Accrued interest	13,059		21,362
Undistributed oil and gas revenues	7,110		7,550
Total Current Liabilities	179,867		177,480
Long-Term Debt	987,168	[1]	916,934	[1]
Deferred Tax Liabilities	226,286		223,243
Asset Retirement Obligation	79,523		79,643
Other Long-Term Liabilities	10,069		9,901
Commitments and Contingencies	0		0
Stockholders' Equity:
Preferred stock, $0.01 par value	0		0
Common stock, $0.01 par value	439		435
Additional paid-in capital	750,697		747,868
Treasury stock held, at cost	(12,471)		(13,855)
Retained earnings	309,621		302,412
Total Stockholders' Equity	1,048,286		1,036,860
Total Liabilities and Stockholders' Equity	$ 2,531,199		$ 2,444,061

[1] Amounts are shown net of any debt discount or premium