Acquisitions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) business	Dec. 31, 2016 USD ($) business	Dec. 31, 2015 USD ($) business
Schedule of Business Acquisitions, by Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 87	$ 30	$ 13
Global Imaging Systems, Equipment dealers [Domain]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Number of Businesses Acquired (in businesses) | business	2	2	2
Business Combination, Acquisition of 100 Percent of acquired company	100.00%	100.00%	100.00%
Revenue of Acquiree since Acquisition Date, Actual	$ 54
Goodwill, Expected Tax Deductible Percentage	100.00%
Accounts/finance receivables	$ 8
Goodwill	44
Other assets	18
Total Assets Acquired	98
Liabilities assumed	(11)
Payments to Acquire Businesses, Net of Cash Acquired	87	$ 30	$ 13
Prior year acquisitions [Member]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Revenue of Acquiree since Acquisition Date, Actual		26	14
Acquisitions made current year minus two years [Member]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Revenue of Acquiree since Acquisition Date, Actual	$ 10	$ 10	$ 3
Customer relationships [Member]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Weighted Average Useful Life (Years) Acquired Finite-lived Intangible Asset	10 years
Customer relationships [Member] | Global Imaging Systems, Equipment dealers [Domain]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Intangible assets:	$ 17
Trademarks
Schedule of Business Acquisitions, by Acquisition [Line Items]
Weighted Average Useful Life (Years) Acquired Finite-lived Intangible Asset	20 years
Trademarks | Global Imaging Systems, Equipment dealers [Domain]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Intangible assets:	$ 10
Non-compete agreements [Member]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Weighted Average Useful Life (Years) Acquired Finite-lived Intangible Asset	3 years
Non-compete agreements [Member] | Global Imaging Systems, Equipment dealers [Domain]
Schedule of Business Acquisitions, by Acquisition [Line Items]
Intangible assets:	$ 1