Acquisitions Acquisitions (narrative) (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
Jan. 31, 2020	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Payments for Other Deposits		$ 503
CHINA \| Huatai Group [Member]
Business Acquisition [Line Items]
Payments for Other Deposits	$ 1,550	$ 503	$ 0
Equity method investment, additional 15.3 ownership percentage obtained		15.30%
Equity Method Investments		$ 2,400

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant