Investments (Securities Lending) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	$ 3,584	$ 3,074
Reinvestment portfolio — estimated fair value	3,642	3,174
Amortized cost
Securities Financing Transaction [Line Items]
Securities on loan	1,961	2,031
Estimated fair value
Securities Financing Transaction [Line Items]
Securities on loan	$ 3,468	$ 2,996

This element represents the estimated fair value of the securities lending reinvestment portfolio.

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount, after the effects of master netting arrangements, of securities loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
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- Definition

Carrying amount of liabilities associated with financial assets accounted for as secured borrowings recognized in the transferor's statement of financial position at the end of each period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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