Investments (Fixed Maturity Securities Pledged And Received As Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 29,205	$ 24,006
Available-for-sale Securities	31,393	23,982
Assets Held-in-trust	694	768
Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	29,239	20,366
Reported Value Measurement [Member]
Debt Securities, Available-for-sale [Line Items]
Assets Held-in-trust	27,290	20,073
Collateral Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Amortized Cost Basis	113	81
Available-for-sale Securities	116	84
Collateral Received Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities	$ 727	$ 617

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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