Discontinued Operations (Details) - Discontinued Operations from Statement of Income - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating expenses
Loss on sale and goodwill impairment	$ 0	$ (3)		$ 0	$ (3)
Loss from discontinued operations, net of tax				$ 0	(80)
Tropical Shipping [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues		62			243
Operating expenses
Cost of goods sold		38			149
Operation and maintenance		20			75
Depreciation and amortization		0			5
Taxes other than income taxes		1			5
Loss on sale and goodwill impairment		5			28
Total operating expenses		64			262
Operating loss		(2)			(19)
Income tax expense		(29)	$ (31)		(61)
Loss from discontinued operations, net of tax		$ (31)			$ (80)