Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2014	$ 131,122
Exchange rate fluctuations	122
Balance at September 30, 2015	136,691
Executive Search and Leadership Consulting [Member] \| Americas [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	5,447
Goodwill [Roll Forward]
Balance at December 31, 2014	81,626
Exchange rate fluctuations	227
Balance at September 30, 2015	87,300
Executive Search and Leadership Consulting [Member] \| Europe [Member]
Goodwill [Roll Forward]
Balance at December 31, 2014	10,745
Exchange rate fluctuations	(270)
Balance at September 30, 2015	10,475
Executive Search and Leadership Consulting [Member] \| Asia Pacific [Member]
Goodwill [Roll Forward]
Balance at December 31, 2014	9,211
Exchange rate fluctuations	214
Balance at September 30, 2015	9,425
Culture Shaping [Member]
Goodwill [Roll Forward]
Balance at December 31, 2014	29,540
Exchange rate fluctuations	(49)
Balance at September 30, 2015	$ 29,491

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
-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

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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.

+ 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

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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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+ References

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Amount of increase (decrease) from foreign currency translation adjustments 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 (f)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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