Amount of unrealized gain (loss) on 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=116654751&loc=SL75117546-209714

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- Definition

Sum of the carrying amounts as of the balance sheet date of all investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(h))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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- Definition

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+ References

No definition available.

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Investments Other Segments and Holding Company (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Investments	$ 8,913	$ 9,945
Other Segments and Holding Company
Schedule of Investments [Line Items]
Investments	674	738
Portion of unrealized (losses) gains that relates to equity securities still held	36	421	$ 339
Equity method investments \| Other Segments and Holding Company
Schedule of Investments [Line Items]
Investments	120	201
Held-to-maturity Securities [Member] \| Other Segments and Holding Company
Schedule of Investments [Line Items]
Investments	20
Other investments \| Other Segments and Holding Company
Schedule of Investments [Line Items]
Investments	$ 534	$ 537