CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 39,169		$ 3,012		$ 270,089	$ 217,569
Accounts receivable	77,210		79,089
Other current assets	60,131		128,571
Total current assets	176,510		210,672
Property and equipment	10,199,475		9,601,102
Less accumulated depreciation, depletion, and amortization	7,938,913		6,949,986
Net property and equipment	2,260,562		2,651,116
Investment in subsidiaries	0		0
Goodwill	239,420		239,420
Due from subsidiaries	0		0
Deferred income taxes	9,851		231,116
Other assets	96,035		48,827
TOTAL ASSETS	2,782,378		3,381,151
Current liabilities:
Accounts payable and accrued liabilities	189,753		247,880
Current portion of long-term debt	296,002	[1]	0	[1]
Other current liabilities	68,016		92,957
Total current liabilities	553,771		340,837
Long-term debt	1,796,369		1,693,044
Due to parent and subsidiaries	0		0
Deferred income taxes	0		0
Other liabilities	189,461		154,157
Total liabilities	2,539,601		2,188,038
Shareholders' equity	242,777		1,193,113
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,782,378		3,381,151
Parent Company
Current assets:
Cash and cash equivalents	39,098		1,734
Accounts receivable	46,533		43,999
Other current assets	59,190		127,667
Total current assets	144,821		173,400
Property and equipment	8,578,281		8,000,466
Less accumulated depreciation, depletion, and amortization	6,611,026		5,782,409
Net property and equipment	1,967,255		2,218,057
Investment in subsidiaries	80,577		160,591
Goodwill	216,460		216,460
Due from subsidiaries	145,817		214,394
Deferred income taxes	100,874		312,564
Other assets	96,035		48,827
TOTAL ASSETS	2,751,839		3,344,293
Current liabilities:
Accounts payable and accrued liabilities	181,923		235,788
Current portion of long-term debt	296,002		0
Other current liabilities	61,574		86,618
Total current liabilities	539,499		322,406
Long-term debt	1,796,369		1,693,044
Due to parent and subsidiaries	0		0
Deferred income taxes	0		0
Other liabilities	173,194		135,730
Total liabilities	2,509,062		2,151,180
Shareholders' equity	242,777		1,193,113
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	2,751,839		3,344,293
Guarantor Subsidiary
Current assets:
Cash and cash equivalents	0		1		0	3
Accounts receivable	26,978		34,142
Other current assets	319		313
Total current assets	27,297		34,456
Property and equipment	1,413,677		1,317,917
Less accumulated depreciation, depletion, and amortization	1,157,456		1,102,339
Net property and equipment	256,221		215,578
Investment in subsidiaries	0		0
Goodwill	22,960		22,960
Due from subsidiaries	58,730		46,944
Deferred income taxes	0		0
Other assets	0		0
TOTAL ASSETS	365,208		319,938
Current liabilities:
Accounts payable and accrued liabilities	2,583		8,846
Current portion of long-term debt	0		0
Other current liabilities	129		63
Total current liabilities	2,712		8,909
Long-term debt	0		0
Due to parent and subsidiaries	0		0
Deferred income taxes	126,087		107,012
Other liabilities	3,650		2,614
Total liabilities	132,449		118,535
Shareholders' equity	232,759		201,403
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	365,208		319,938
Combined Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	71		1,277		704	986
Accounts receivable	4,161		2,201
Other current assets	622		591
Total current assets	4,854		4,069
Property and equipment	207,517		282,719
Less accumulated depreciation, depletion, and amortization	170,431		65,238
Net property and equipment	37,086		217,481
Investment in subsidiaries	0		0
Goodwill	0		0
Due from subsidiaries	0		0
Deferred income taxes	35,064		25,564
Other assets	0		0
TOTAL ASSETS	77,004		247,114
Current liabilities:
Accounts payable and accrued liabilities	5,709		4,499
Current portion of long-term debt	0		0
Other current liabilities	6,313		6,276
Total current liabilities	12,022		10,775
Long-term debt	0		0
Due to parent and subsidiaries	204,547		261,338
Deferred income taxes	0		0
Other liabilities	12,617		15,813
Total liabilities	229,186		287,926
Shareholders' equity	(152,182)		(40,812)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	77,004		247,114
Eliminations
Current assets:
Cash and cash equivalents	0		0
Accounts receivable	(462)		(1,253)
Other current assets	0		0
Total current assets	(462)		(1,253)
Property and equipment	0		0
Less accumulated depreciation, depletion, and amortization	0		0
Net property and equipment	0		0
Investment in subsidiaries	(80,577)		(160,591)
Goodwill	0		0
Due from subsidiaries	(204,547)		(261,338)
Deferred income taxes	(126,087)		(107,012)
Other assets	0		0
TOTAL ASSETS	(411,673)		(530,194)
Current liabilities:
Accounts payable and accrued liabilities	(462)		(1,253)
Current portion of long-term debt	0		0
Other current liabilities	0		0
Total current liabilities	(462)		(1,253)
Long-term debt	0		0
Due to parent and subsidiaries	(204,547)		(261,338)
Deferred income taxes	(126,087)		(107,012)
Other liabilities	0		0
Total liabilities	(331,096)		(369,603)
Shareholders' equity	(80,577)		(160,591)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ (411,673)		$ (530,194)

[1] In September 2012, the Company irrevocably called $300.0 million (50% of the aggregate principal amount) of the 8½% senior notes due 2014 and redeemed those called notes in October 2012 at 110.24% of par, recognizing a loss of $36.3 million upon redemption.