Summary of Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Purchases of available-for-sale investment securities		$ 28,000,000	$ 64,000,000
Capitalized Software Development Costs [Abstract]
Capitalized software development costs	0	4,000,000
Amortization of capitalized software development costs	3,000,000	8,000,000	10,000,000
Capitalized software development costs included in other assets	2,000,000	5,000,000
Deferred Costs, Leasing, Net [Abstract]
Amortization of initial direct costs	10,000,000	11,000,000	13,000,000
Initial direct costs included in rental property and equipment	22,000,000	26,000,000
Marketing and Advertising Expense [Abstract]
Capitalization period for deferred marketing costs	8 years
Deferred costs expensed	23,000,000	27,000,000	30,000,000
Deferred marketing costs included in other assets	$ 49,000,000	$ 59,000,000
Minimum
Property, Plant and Equipment [Line Items]
Finite-lived intangible assets, estimated useful lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Finite-lived intangible assets, estimated useful lives	15 years
Buildings
Property, Plant and Equipment [Line Items]
Estimated useful lives	P50Y
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P3Y
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P15Y
Rental equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P4Y
Rental equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P6Y
Computer equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P3Y
Computer equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P5Y
Software development costs | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P3Y
Software development costs | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P10Y
Purchased materials, services, payroll, and personnel-related costs attributable to programmers, software engineers, quality control and field certifiers | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P3Y
Purchased materials, services, payroll, and personnel-related costs attributable to programmers, software engineers, quality control and field certifiers | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	P5Y