Acquisitions (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 02, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Net cash paid for acquisition		$ 340	$ 18
Assets acquired
Goodwill		$ 6,376		$ 6,200
ECM S.p.A.
Business Acquisition [Line Items]
Percentage of equity acquired (as a percent)	100.00%
Net cash paid for acquisition	$ 225
Cash paid at closing	249
Assets acquired
Cash	25
Receivables	31
Inventory	29
Property, plant, and equipment	17
Finite-lived intangible assets	$ 112
Finite-lived intangible assets, weighted average useful life (in years)	13 years
Tangible assets	$ 107
Goodwill	112
Total liabilities assumed	80
Debt assumed	1
Accounts payable	38
Deferred tax liabilities	25
Downer Freight Rail
Business Acquisition [Line Items]
Net cash paid for acquisition	99
Assets acquired
Receivables	26
Inventory	42
Property, plant, and equipment	17
Finite-lived intangible assets	5
Finite-lived customer relationship intangible assets	$ 5
Finite-lived intangible assets, weighted average useful life (in years)	15 years
Tangible assets	$ 92
Goodwill	12
Total liabilities assumed	$ 10