Income Taxes (Legislative Changes Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Deferred foreign tax expense (benefit)		$ (33)	$ (6)	$ 153
Current foreign tax expense (benefit)		$ 152	$ 56	83
MEXICO
Income Taxes [Line Items]
Mexico federal statutory tax rate	30.00%
Deferred foreign tax expense (benefit)				(46)
Current foreign tax expense (benefit)				27
Foreign tax expense (benefit)				$ (19)