Income Taxes (Details) $ in Millions, $ in Billions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Aug. 31, 2016 USD ($)	Aug. 31, 2016 MXN ($)
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective income tax rate, continuing operations	41.30%	32.90%
Impact of foreign exchange	6.00%	12.70%
Other reconciling items	15.40%	14.10%
Timing and mix of pretax income with rates differing from US	(1.10%)	(28.90%)
Mexican Tax Authority | Tax Year 2010
Income Tax Contingency [Line Items]
Number of subsidiaries in a tax assessment			1	1
Tax assessment			$ 157	$ 3