CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 17,508	$ 53,583
Restricted cash	7,108	8,542
Accounts receivable	387,324	377,638
Inventories	30,408	28,141
Hedging asset	133,012	282,693
Other	41,447	58,315
Total current assets	616,807	808,912
Property and Equipment:
Natural gas and oil properties, using the full cost method, including $1,090.1 million in 2013 and $1,023.9 million in 2012 excluded from amortization	11,766,978	11,283,114
Gathering systems	1,187,153	1,148,261
Other	607,607	597,064
Less: Accumulated depreciation, depletion and amortization	(7,380,230)	(7,191,463)
Total property and equipment, net	6,181,508	5,836,976
Other Assets	118,476	91,639
TOTAL ASSETS	6,916,791	6,737,527
Current liabilities:
Accounts payable	553,147	459,569
Taxes payable	48,803	62,980
Interest payable	14,185	34,431
Advances from partners	24,511	68,919
Current deferred income taxes	48,932	106,123
Other current liabilities	41,896	35,749
Total current liabilities	731,474	767,771
Long-term debt	1,703,403	1,668,273
Other Liabilities:
Deferred income taxes	1,131,312	1,049,138
Pension and other postretirement liabilities	33,773	33,174
Other long-term liabilities	235,021	183,299
Total long-term liabilities	3,103,509	2,933,884
Equity:
Common stock, $0.01 par value; authorized 1,250,000,000 shares; issued 350,415,917 shares in 2012 and 349,058,501 in 2011	3,516	3,511
Additional paid-in capital	946,512	934,939
Retained earnings	2,076,665	1,949,150
Accumulated other comprehensive income	55,607	149,804
Common stock in treasury, 14,223 shares in 2013 and 64,715 in 2012	(492)	(1,532)
Total equity	3,081,808	3,035,872
TOTAL LIABILITIES AND EQUITY	$ 6,916,791	$ 6,737,527