Accounting Policies - Revenue, Initial Application Period Cumulative Effect Transition (Details) - Difference between Revenue Guidance in Effect before and after Topic 606 [Member] $ in Billions	9 Months Ended
	Sep. 30, 2018 USD ($)
Service, Subscription [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ 2.6
Product, Subscription [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	(2.6)
Service, Other [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ 2.0