Condensed Consolidated Statements of Income (Unaudited) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues
Sales	$ 1,797.2	$ 1,682.2	$ 5,282.0	$ 5,029.4
Other revenues	261.6	298.4	778.6	636.7
Total revenues	2,058.8	1,980.6	6,060.6	5,666.1
Costs and expenses
Operating costs and expenses	1,509.0	1,399.4	4,396.8	3,958.7
Depreciation, depletion and amortization	(172.5)	(108.4)	(470.7)	(317.6)
Asset retirement obligation expenses	21.1	14.6	53.3	43.3
Selling and administrative expenses	68.7	71.2	202.4	191.4
Other operating (income) loss:
Net gain on disposal or exchange of assets	(0.2)	(1.7)	(7.6)	(31.4)
Loss from equity affiliates	21.2	3.2	50.5	9.0
Operating profit	266.5	385.5	894.5	1,177.5
Interest expense	99.4	59.2	308.3	159.1
Interest income	(5.1)	(4.1)	(19.7)	(11.7)
Income from continuing operations before income taxes	(172.2)	(330.4)	(605.9)	(1,030.1)
Income tax provision	49.3	39.2	85.5	238.8
Income from continuing operations, net of income taxes	122.9	291.2	520.4	791.3
Loss from discontinued operations, net of income taxes	(81.3)	(9.7)	(92.7)	(38.9)
Net income	41.6	281.5	427.7	752.4
Less: Net (loss) income attributable to noncontrolling interests	(1.3)	7.4	7.4	17.0
Net income attributable to common stockholders	42.9	274.1	420.3	735.4
Income From Continuing Operations
Basic earnings per share	$ 0.46	$ 1.05	$ 1.89	$ 2.86
Diluted earnings per share	$ 0.46	$ 1.04	$ 1.89	$ 2.84
Net Income Attributable to Common Stockholders
Basic earnings per share	$ 0.16	$ 1.01	$ 1.55	$ 2.72
Diluted earnings per share	$ 0.16	$ 1.00	$ 1.55	$ 2.71
Dividends declared per share	$ 0.085	$ 0.085	$ 0.255	$ 0.255
Retained Earnings [Member]
Other operating (income) loss:
Net income			$ 420.3