Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Consolidated Statements of Comprehensive Income Parenthetical [Abstract]
Unrecognized amounts on retirement benefits, tax	$ (7)	$ (4)
Unrealized (losses) gains on marketable securities, tax	0	0
Unrealized (losses) gains on cash flow hedges, tax	$ (2)	$ (1)

Consolidated Statements of Comprehensive Income Parenthetical [Abstract]

No definition available.

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- Definition

Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e640-108580

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- Definition

Amount of tax expense (benefit), after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e640-108580

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- Definition

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
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-Name Accounting Standards Codification
-Topic 810
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