Financial Instruments (Schedule Of Investment Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Held to maturity
Cost	$ 30	$ 26
Unrealized Gains	1	0
Unrealized Losses	0	0
Securities held to maturity	$ 31	$ 26

Amount of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Publisher FASB
-Name Accounting Standards Codification
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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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