Summary of Significant Accounting Policies - Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2017
Equipment on lease
Property, Plant and Equipment [Line Items]
Estimated useful life	35 years
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Machinery and other | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Machinery and other | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Technology equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Technology equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years