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Post-Employment and Other Long-Term Employees Benefits - Accumulated Other Comprehensive Income (Loss) Before Tax Effects (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Retirement Benefits [Abstract] |  |
Other comprehensive loss, actuarial (gains)/losses, beginning balance | $ 139 | $ 137
Net amount generated/arising in current year, actuarial (gains)/losses | 6 | 25
Amortization, actuarial (gains)/losses | (10) | (14)
Foreign currency translation, actuarial (gains)/losses before tax | 9 | (9)
Other comprehensive loss, actuarial (gains)/losses, ending balance | 144 | 139
Other comprehensive loss, prior service cost, beginning balance | 2 | 3
Net amount generated/arising in current year, prior service cost | 0 | 0
Amortization, prior service cost |  | (1)
Foreign currency translation adjustment | 0 | 0
Other comprehensive loss, prior service cost, ending balance | 2 | 2
Other comprehensive loss, Total, beginning balance | 141 | 140
Net amount generated/arising in current year, Total | 6 | 25
Amortization, Total | (10) | (15)
Foreign currency translation adjustment, Total | 9 | (9)
Other comprehensive loss, Total, ending balance | $ 146 | $ 141

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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i-k) -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580 + Details
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