Discontinued Operations Assets And Liabilities Of Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 1,160.1	$ 30.0	$ 0	$ 0
Accounts receivable, net	441.9	330.3
Deferred income taxes - current	0	27.9
Prepaid expenses and other	46.8	45.4
Current assets of discontinued operations	0	122.0
Materials and supplies	54.3	54.3
Property, Plant and Equipment, Gross	13,452.0	12,573.6
Other noncurrent assets	44.2	46.6
Production and property taxes	61.7	54.7
Current liabilities of discontinued operations	0	75.3
Deferred Tax Liabilities, Net, Noncurrent	1,362.7	1,364.9
Asset retirement obligations	193.8	163.3
Other long-term liabilities	92.1	94.5
Noncurrent liabilities of discontinued operations	0	238.3
Midstream Business Held For Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and Cash Equivalents, at Carrying Value		18.1
Accounts receivable, net		53.9
Income Taxes Receivable, Current		38.4
Deferred income taxes - current		2.7
Prepaid expenses and other		8.9
Current assets of discontinued operations		122.0
Midstream Field Services Property		1,500.8
Materials and supplies		4.8
Property, Plant and Equipment, Gross		1,505.6
Accumulated Depreciation Midstream Field Services		(381.6)
Net Property, Plant and Equipment		1,124.0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		39.0
Other noncurrent assets		4.7
Noncurrent assets of discontinued operations		1,167.7
Accounts payable and accrued expenses		74.1
Production and property taxes		1.2
Current liabilities of discontinued operations		75.3
Deferred Tax Liabilities, Net, Noncurrent		195.7
Asset retirement obligations		28.5	37.5
Other long-term liabilities		14.1
Noncurrent liabilities of discontinued operations		$ 238.3