Income Taxes Income Taxes (Details) $ in Millions, MXN in Billions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Aug. 31, 2016 USD ($)	Aug. 31, 2016 MXN
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective income tax rate, continuing operations	32.90%	(23.80%)
Timing and mix of pretax income with rates lower than US	(28.90%)	(65.30%)
Impact of foreign exchange	12.70%	(3.60%)
Other reconciling items	14.10%	10.10%
Mexican Tax Authority [Member] | Tax Year 2010 [Member]
Income Tax Contingency [Line Items]
Tax assessment			$ 157	MXN 3