Income Taxes - Unrecognized Tax Benefits, Including Attributable to Discontinued Operations (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense (Benefit) [Rollforward]
Balance at January 1	$ 76	$ 76
Additions based on tax positions related to current year	4	4
Additions for tax positions of prior years	3	1
Reductions for tax positions of prior years	(8)	0
Settlements and agreements	(1)	(2)
Lapse of statute of limitations	(4)	(3)
Balance at December 31	$ 70	$ 76

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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