Expenses - Restructuring Reserve (Details) - State Street Beacon - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning balance	$ 82	$ 108	$ 23	$ 23
Accruals for State Street Beacon	10	13	97	120
Payments and Other Adjustments	(18)	(39)	(12)
Ending balance	74	82	108	74
Employee Related Costs
Restructuring Reserve [Roll Forward]
Beginning balance	55	91	9	9
Accruals for State Street Beacon	8	(1)	86
Payments and Other Adjustments	(14)	(35)	(4)
Ending balance	49	55	91	49
Real Estate Consolidation
Restructuring Reserve [Roll Forward]
Beginning balance	22	10	11	11
Accruals for State Street Beacon	3	15	0
Payments and Other Adjustments	(3)	(3)	(1)
Ending balance	22	22	10	22
Asset and Other Write-offs
Restructuring Reserve [Roll Forward]
Beginning balance	5	7	3	3
Accruals for State Street Beacon	(1)	(1)	11
Payments and Other Adjustments	(1)	(1)	(7)
Ending balance	$ 3	$ 5	$ 7	$ 3

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.P.3)
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140864-122747

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

+ Details

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- Definition

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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