Investments Schedule of Gains and Losses on Equity and Other Investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gain (Loss) on Securities [Line Items]
Realized Investment Gains (Losses)	$ (21)	$ (141)	$ 833	$ (1,069)
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Equity Securities, FV-NI, Realized Gain (Loss)	(42)	0	475	119
Less: Net gains (losses) recognized from sales of securities	19	34	109	197
Unrealized gains (losses) recognized for securities still held at reporting date	(61)	(34)	366	(78)
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Realized Investment Gains (Losses)	11	31	111	(71)
Less: Net gains (losses) recognized from sales of securities	0	0	0	0
Unrealized gains (losses) recognized for securities still held at reporting date	11	31	111	(71)
Equity securities and other investments [Member]
Gain (Loss) on Securities [Line Items]
Realized Investment Gains (Losses)	(31)	31	586	48
Less: Net gains (losses) recognized from sales of securities	19	34	109	197
Unrealized gains (losses) recognized for securities still held at reporting date	$ (50)	$ (3)	$ 477	$ (149)

Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123583765&loc=SL75117546-209714

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(d))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

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-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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