Discontinued Operations (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Value of midstream business sold				$ 2,500.0
Debt Refinanced In Business Sale				230.0
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax				1,800.0
Discontinued Operation, Amount of Continuing Cash Flows after Disposal		$ 69.3	$ 74.0
Employee Retention Bonus Cost				$ 10.4
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) Attributable to Parent	$ 5.7		12.5
Depreciation, depletion and amortization	14.5		28.8
Payments to Acquire Oil and Gas Property and Equipment	24.4		37.1
Employee Retention Bonus Cost	$ 2.6		$ 4.8