Acquisitions and Divestitures - Acquisitions (Details) $ in Millions	1 Months Ended	6 Months Ended
	Oct. 31, 2017 USD ($)	Jun. 30, 2018 USD ($) item	Jun. 30, 2017 item
Supplemental information:
Cash paid, net of cash acquired		$ (13)
Number of business combinations completed | item		0	0
Scott Safety
Supplemental information:
Cash paid, net of cash acquired	$ 2,000
Adjustments to purchase price allocation		$ 16