CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Current Assets
Cash and cash equivalents	$ 0	$ 0
Accounts receivable, net	355.3	269.9
Fair value of derivative contracts	225.4	257.3
Inventories, at lower of average cost or market
Gas, oil and NGL	16.1	16.4
Materials and supplies	87.1	65.4
Prepaid expenses and other	35.6	45.2
Total Current Assets	719.5	654.2
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	7,780.8	6,874.3
Unproved properties, not being depleted	326.3	322.0
Midstream field services	1,430.6	1,360.5
Marketing and other	47.8	44.5
Total Property, Plant and Equipment	9,585.5	8,601.3
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	2,963.6	2,454.4
Midstream field services	283.7	244.6
Marketing and other	14.0	12.3
Total Accumulated Depreciation, Depletion and Amortization	3,261.3	2,711.3
Net Property, Plant and Equipment	6,324.2	5,890.0
Investment in unconsolidated affiliates	44.1	44.5
Goodwill	59.5	59.6
Fair value of derivative contracts	116.4	120.8
Other noncurrent assets	33.2	16.2
TOTAL ASSETS	7,296.9	6,785.3
Current Liabilities
Checks outstanding in excess of cash balances	26.7	19.5
Accounts payable and accrued expenses	455.3	332.2
Production and property taxes	40.4	18.9
Interest payable	6.2	28.1
Fair value of derivative contracts	39.8	139.3
Deferred income taxes	20.7	27.8
Current portion of long-term debt	0	58.5
Total Current Liabilities	589.1	624.3
Long-term debt, less current portion	1,582.7	1,472.3
Deferred income taxes	1,535.0	1,377.7
Asset retirement obligations	160.2	148.3
Fair value of derivative contracts	0	0.3
Other long-term liabilities	103.3	99.3
Commitments and contingencies
EQUITY
Common stock	1.8	1.8
Treasury stock	(11.6)	(3.8)
Additional paid-in capital	423.9	398.0
Retained earnings	2,677.2	2,420.0
Accumulated other comprehensive income	184.4	194.3
Total Common Shareholders' Equity	3,275.7	3,010.3
Noncontrolling interest	50.9	52.8
Total Equity	3,326.6	3,063.1
TOTAL LIABILITIES AND EQUITY	$ 7,296.9	$ 6,785.3