Summary of Accounting Policies - Internal Use Software Assets/Accounts Payable (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capitalized software development costs, net of amortization	$ 79	$ 66
Capitalized Computer Software, Amortization	$ 15	12	$ 13
Minimum [Member]
Finite useful life of intangible assets	3 years
Minimum [Member] \| Software Development
Finite useful life of intangible assets	3 years
Maximum [Member]
Finite useful life of intangible assets	50 years
Maximum [Member] \| Software Development
Finite useful life of intangible assets	12 years
Accounts Payable
Accounts payable	$ 77	99
Accrued compensation	$ 20	$ 27

Carrying value as of the balance sheet date of payments made in excess of existing cash balances, which will be honored by the bank but reflected as a loan to the entity. Overdrafts generally have a very short time frame for correction or repayment and are therefore more similar to short-term bank financing than trade financing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1243-112600

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

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The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

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