Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Segment Information (Narrative) (Details) $ in Millions	3 Months Ended								12 Months Ended
Segment Information (Narrative) (Details) $ in Millions	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of segments \| Segment									5
Segment Reporting Information [Line Items]
Revenues	$ 19,418	$ 16,015	$ 14,099	$ 18,310	$ 17,143	$ 18,678	$ 17,497	$ 16,302	$ 67,842	$ 69,620	$ 67,941
Total assets	795,146				740,463				$ 795,146	$ 740,463
Concentration Risk, Percentage									10.00%	10.00%	10.00%
Japan
Segment Reporting Information [Line Items]
Total assets	$ 146,000				$ 134,000				$ 146,000	$ 134,000
Assets, Total \| Geographic Concentration Risk \| Japan
Segment Reporting Information [Line Items]
Concentration Risk, Percentage									18.00%	18.00%
One U.S. Customer \| UNITED STATES
Segment Reporting Information [Line Items]
Revenues											$ 6,000
One U.S. Customer \| Sales \| UNITED STATES
Segment Reporting Information [Line Items]
Concentration Risk, Percentage											12.00%