Summary of Significant Accounting Policies (Property, Plant and Equipment - Estimated Useful Lives) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation	$ 1,300	$ 1,300	$ 1,200
Buildings and leasehold improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	10 years
Buildings and leasehold improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	40 years
Rental and service equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	2 years
Rental and service equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	20 years
Machinery and other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	2 years
Machinery and other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	12 years