Products and Services Revenues - Capitalized Contract Costs (Details) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Capitalized Contract Cost [Roll Forward]
End of period balance	$ 126
Contract Acquisition Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	91
Costs incurred	14
Amortization	(15)
End of period balance	90
Contract Fulfillment Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	37
Costs incurred	4
Amortization	(5)
End of period balance	$ 36

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

Name:	us-gaap_CapitalizedContractCostNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant