Regulatory Matters and Capital Adequacy (Details Textuals) $ in Billions	12 Months Ended
Dec. 31, 2017 USD ($)
Regulatory Matters And Capital Adequacy [Abstract]
Restricted net assets of subsidiaries	$ 9.3
Amount Available for Dividend Distribution without Affecting Capital Adequacy Requirements	3.8
American Express Centurion Bank [Member]
Regulatory Matters And Capital Adequacy [Abstract]
Dividends paid from retained earnings to its parent company	1.9
American Express Bank, FSB [Member]
Regulatory Matters And Capital Adequacy [Abstract]
Dividends paid from retained earnings to its parent company	$ 2.6

Regulatory matters and capital adequacy.

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- Definition

The amount of dividends that can be declared or paid without affecting the banking or savings institution's regulatory capital position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

This element represents disclosure of the total aggregate cash dividends paid to the entity by consolidated subsidiaries, by unconsolidated subsidiaries, and by 50% or less owned persons accounted for using the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.9-06)
-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537971-122884

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