Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jan. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations before income taxes	$ 1.2	$ (16.1)	$ 1.1	$ (32.7)
Income tax provision (benefit)	0.4	(1.8)	0.1	(9.3)
Income (loss) from discontinued operations, net of income taxes	0.8	(14.3)	1.0	(23.4)
Total revenues associated with discontinued operations	0	35.6	0	67.7
Other current assets	2.4		2.4			38.6
Investments and other assets	20.8		20.8			47.4
Total assets classified as discontinued operations	23.2		23.2			86.0
Accounts payable and accrued expenses	42.3		42.3			127.8
Other noncurrent liabilities	86.7		86.7			90.2
Total liabilities classified as discontinued operations	129.0		129.0			218.0
Payment to Patriot based on the construct of the negotiated settlement					70.0
Asset retirement obligation	721.2		721.2			712.8
Proceeds from sale of property held-for-sale	70		70
Wilkie Creek [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liability balance	29.3		29.3			36.6
Change in estimate			(0.2)
Cash payments			(8.7)
Foreign currency remeasurement expense			1.6
Asset retirement obligation	48.0		48.0
Wilkie Creek [Member] | Other Exit Costs [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liability balance	0.1		0.1			2.7
Change in estimate			(0.2)
Cash payments			(2.4)
Foreign currency remeasurement expense			0
Wilkie Creek [Member] | Accrued Take or Pay Liabilities [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liability balance	29.2		29.2			33.9
Change in estimate			0
Cash payments			(6.3)
Foreign currency remeasurement expense			$ 1.6