Goodwill and Other Intangible Assets - Rollforward of Goodwill by Operating Segment (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 14,342	$ 201
Adjustments	(6)	(1)
Goodwill	24,154	9,818	$ 9,618
CB-Retail
Goodwill [Line Items]
Goodwill, Acquired During Period	10,134	0
Adjustments	0	(1)
Goodwill	14,040	3,906	3,907
CB-Commercial
Goodwill [Line Items]
Goodwill, Acquired During Period	4,187	0
Adjustments	0	0
Goodwill	8,125	3,938	3,938
IH
Goodwill and Intangible Assets Disclosure [Abstract]
Identifiable intangible assets acquired		175
Goodwill [Line Items]
Goodwill, Acquired During Period	21	201
Adjustments	(6)	0
Goodwill	$ 1,989	$ 1,974	$ 1,773

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 45
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
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