Earnings Per Share (EPS) (Income from Participating Securities) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share
Net income attributable to participating securities	$ 32	$ 30	$ 24
Continuing Operations [Member]
Earnings Per Share
Net income attributable to participating securities	32	30	24
Discontinued Operations [Member]
Earnings Per Share
Net income attributable to participating securities	$ 0	$ 0	$ 0

Amount of earnings (loss) distributed and earnings (loss) allocated to participating securities for the basic earnings (loss) per share or per unit calculation under the two-class method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256

Name:	us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration