Recent Accounting Pronouncements (Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment, Net of tax	$ 15
Impact of adoption of new accounting principle	11
Accounting Standards Update 2018-11 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment, Net of tax	15
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting principle	$ (79)

Amount of the cumulative effect on retained earnings before related income tax effect.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122869-111746

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