Acquisitions Acquisitions (narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Business Acquisition [Line Items]
Payments for Other Deposits	$ 1,550	$ 0
CHINA \| Huatai Group [Member]
Business Acquisition [Line Items]
Payments for Other Deposits	$ 1,550

Amount of cash outflow for deposits classified as other.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

Name:	us-gaap_PaymentsForOtherDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration