Investments - Total unrealized losses and limited partnerships narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Limited partnerships
Limited partnership interests	$ 3,250	$ 3,292
Equity method limited partnerships
Limited partnerships
Limited partnership interests	2,480	2,510
Carrying value \| Cost method limited partnership interests
Limited partnerships
Limited partnership interests	$ 773	$ 787

Amount of investment in equity method investee and investment in and advance to affiliate.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant