Goodwill and Other Intangible Assets - Summary of Other Intangible Assets Net by Segment (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 1,554,000	$ 1,935,000
Goodwill	123,422,000	126,831,000
Executive Search [Member] | Americas [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	372,000	557,000
Goodwill	91,338,000	92,497,000
Executive Search [Member] | Europe [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	1,130,000	1,314,000
Goodwill	24,196,000	25,579,000
Executive Search [Member] | Asia Pacific [Member]
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	52,000	64,000
Goodwill	$ 7,888,000	$ 8,755,000