Goodwill and Other Intangible Assets, Net - Summary of Changes in Carrying Amount of Goodwill by Reportable Segment (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Goodwill [Line Items]
Beginning balance	$ 863,881
Acquisitions	74,322	$ 37,100
Measurement period adjustments	(16,276)
Cumulative translation adjustment	4,857
Ending balance	926,784	863,881
Financial Services [Member]
Goodwill [Line Items]
Beginning balance	451,035
Acquisitions	29,049
Measurement period adjustments	(17,057)
Cumulative translation adjustment	4,857
Ending balance	467,884	451,035
Real Estate Services [Member]
Goodwill [Line Items]
Beginning balance	412,846
Acquisitions	45,273
Measurement period adjustments	781
Ending balance	$ 458,900	$ 412,846

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.

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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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e961-128460

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