Quarterly Financial Data (unaudited) - Textuals (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Reversal of income tax valuation allowance			$ 731
Litigation settlement charge		$ 48	0	$ 48	$ 0
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges		$ 30	0	90	0
Contract termination charge and (recovery) loss on receivable	$ 15		(6)	15	0
Pension settlement charges	13		$ 1	13	$ 16
Self-unloading ocean vessels
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges	$ 60			$ 60