Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Comprehensive Income (Loss)
(Losses) on cash-flow hedges, income tax benefit	$ 5
(Losses) gains on cash flow hedges, income tax benefit (expense)		$ (2)	$ 6
Losses on cash-flow hedges reclassified to earnings, income tax benefit (expense)	(4)
Losses on cash flow hedges reclassified to earnings, income tax benefit (expense)		(2)	(2)
Actuarial gains (losses) on pension and other postretirement obligations, settlements and plan amendments, income tax (expense) benefit	$ (2)	$ 5	(2)
Gains related to pension and other postretirement obligations reclassified to earnings, income tax benefit (expense)			1
Unrealized gains on investments, income tax (expense) benefit			$ (1)

Amount of tax expense (benefit) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
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Amount, before reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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Amount of tax expense (benefit), before reclassification adjustments, related to 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).

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