Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Comprehensive Income Parenthetical [Abstract]
Unrecognized amounts on retirement benefits, tax	$ 0	$ 1	$ 12	$ (3)
Unrealized (losses) gains on marketable securities, tax	0	284	0	355
Unrealized (losses) gains on cash flow hedges, tax	$ (1)	$ 1	$ (1)	$ (3)

Consolidated Statements of Comprehensive Income Parenthetical [Abstract]

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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

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-Topic 220
-SubTopic 10
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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

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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.

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-Publisher FASB
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