Condensed Consolidated Balance Sheets (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents
Accounts receivable, net	340.7	269.9
Fair value of derivative contracts	183.8	257.3
Inventories, at lower of average cost or market
Gas and oil storage	11.7	16.4
Materials and supplies	85.8	65.4
Prepaid expenses and other	33.6	45.2
Total Current Assets	655.6	654.2
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	7,503.8	6,874.3
Unproved properties, not being depleted	323.1	322.0
Midstream field services	1,393.1	1,360.5
Marketing and other	45.6	44.5
Total Property, Plant and Equipment	9,265.6	8,601.3
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	2,800.2	2,454.4
Midstream field services	270.2	244.6
Marketing and other	13.3	12.3
Total Accumulated Depreciation, Depletion and Amortization	3,083.7	2,711.3
Net Property, Plant and Equipment	6,181.9	5,890.0
Investment in unconsolidated affiliates	44.0	44.5
Goodwill	59.6	59.6
Fair value of derivative contracts	109.3	120.8
Other noncurrent assets	24.6	16.2
TOTAL ASSETS	7,075.0	6,785.3
LIABILITIES AND EQUITY
Checks outstanding in excess of cash balances	18.0	19.5
Accounts payable and accrued expenses	430.6	332.2
Production and property taxes	31.4	18.9
Interest payable	24.9	28.1
Fair value of derivative contracts	75.8	139.3
Deferred income taxes	2.2	27.8
Current portion of long-term debt		58.5
Total Current Liabilities	582.9	624.3
Long-term debt, less current portion	1,572.6	1,472.3
Deferred income taxes	1,470.3	1,377.7
Asset retirement obligations	155.7	148.3
Fair value of derivative contracts		0.3
Other long-term liabilities	109.1	99.3
Commitments and contingencies
EQUITY
Common stock	1.8	1.8
Treasury stock	(10.8)	(3.8)
Additional paid-in capital	416.7	398.0
Retained earnings	2,579.4	2,420.0
Accumulated other comprehensive income	145.7	194.3
Total Common Shareholders' Equity	3,132.8	3,010.3
Noncontrolling interests	51.6	52.8
Total Equity	3,184.4	3,063.1
TOTAL LIABILITIES AND EQUITY	$ 7,075.0	$ 6,785.3