Segment Information - Revenue, Operating Income, Depreciation and Amortization, and Capital Expenditures, by Segment (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Revenue:      
Revenue before reimbursements (net revenue) $ 531,139 $ 494,292 $ 461,995
Reimbursements 17,172 18,947 18,998
Total revenue 548,311 513,239 480,993
Operating income:      
Operating (loss) income 34,062 26,653 15,565
Total 34,062 26,653 15,565
Depreciation and amortization      
Depreciation and amortization 13,696 15,312 16,275
Capital expenditures:      
Capital expenditures 15,863 5,835 3,731
Operating Segments [Member]      
Operating income:      
Operating (loss) income 80,662 71,995 53,121
Depreciation and amortization      
Depreciation and amortization 11,684 13,402 14,544
Capital expenditures:      
Capital expenditures 9,680 3,901 3,286
Global Operations Support [Member]      
Operating income:      
Global Operations Support (46,600) (45,342) (37,556)
Depreciation and amortization      
Depreciation and amortization 2,012 1,910 1,731
Capital expenditures:      
Capital expenditures 6,183 1,934 445
Executive Search and Leadership Consulting [Member] | Operating Segments [Member]      
Revenue:      
Revenue before reimbursements (net revenue) 494,812 459,541 437,205
Operating income:      
Operating (loss) income 75,749 67,374 57,336
Depreciation and amortization      
Depreciation and amortization 7,164 8,077 8,806
Capital expenditures:      
Capital expenditures 9,585 3,848 3,286
Culture Shaping [Member] | Operating Segments [Member]      
Revenue:      
Revenue before reimbursements (net revenue) 36,327 34,751 24,790
Operating income:      
Operating (loss) income 4,913 4,621 (4,215)
Depreciation and amortization      
Depreciation and amortization 4,520 5,325 5,738
Capital expenditures:      
Capital expenditures 95 53 13
Executive Search and Leadership Consulting Americas Segment [Member] | Executive Search and Leadership Consulting [Member] | Operating Segments [Member]      
Revenue:      
Revenue before reimbursements (net revenue) 300,473 260,830 256,706
Operating income:      
Operating (loss) income 67,672 57,682 60,171
Depreciation and amortization      
Depreciation and amortization 3,896 2,942 3,672
Capital expenditures:      
Capital expenditures 7,500 2,858 1,411
Executive Search and Leadership Consulting Europe Segment [Member] | Executive Search and Leadership Consulting [Member] | Operating Segments [Member]      
Revenue:      
Revenue before reimbursements (net revenue) 100,606 108,979 90,081
Operating income:      
Operating (loss) income 2,234 4,806 (6,513)
Depreciation and amortization      
Depreciation and amortization 1,845 3,279 2,853
Capital expenditures:      
Capital expenditures 999 478 822
Executive Search and Leadership Consulting Asia Pacific Segment [Member] | Executive Search and Leadership Consulting [Member] | Operating Segments [Member]      
Revenue:      
Revenue before reimbursements (net revenue) 93,733 89,732 90,418
Operating income:      
Operating (loss) income 5,843 4,886 3,678
Depreciation and amortization      
Depreciation and amortization 1,423 1,856 2,281
Capital expenditures:      
Capital expenditures $ 1,086 $ 512 $ 1,053