Income Taxes (Unrecognized Tax Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 11	$ 13	$ 12
Increases related to tax positions taken during a prior period	0	2	2
Increases related to tax positions taken during the current period	1	0	1
Decreases related to settlements with taxing authorities	0	(3)	0
Decreases as a result of a lapse of the applicable statute of limitations	(3)	(1)	(2)
Decreases related to tax positions taken during a prior period	0	0	0
Ending balance	9	11	13
Accrued penalties	1	1	1
Accrued interest	2	2	3
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 1	$ 1	$ (1)

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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-Name Accounting Standards Codification
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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return.

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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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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Amount of interest expense accrued for an underpayment of income taxes.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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