Goodwill and Intangible Assets - Schedule of Goodwill by Reportable Segment (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($)
Goodwill [Line Items]
Goodwill at December 31, 2015	$ 1,565,621
Changes to goodwill	(50)
Foreign exchange translation adjustment	(7,140)
Goodwill at September 30, 2016	1,558,431
Index [Member]
Goodwill [Line Items]
Goodwill at December 31, 2015	1,210,366
Foreign exchange translation adjustment	(4,408)
Goodwill at September 30, 2016	1,205,958
Analytics [Member]
Goodwill [Line Items]
Goodwill at December 31, 2015	302,551
Changes to goodwill	60
Goodwill at September 30, 2016	302,611
All Other [Member]
Goodwill [Line Items]
Goodwill at December 31, 2015	52,704
Changes to goodwill	(110)
Foreign exchange translation adjustment	(2,732)
Goodwill at September 30, 2016	$ 49,862

Goodwill period increase decrease excluding translation adjustments.

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- Definition

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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