v3.26.3
Operating Segments - Schedule of Information by Reportable Segment (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting Information [Line Items]            
Total revenues $ 86,107   $ 94,295   $ 271,794 $ 295,830
Income (loss) from operations 2,381   4,457   (12,851) (76,178)
Selling, marketing, administrative and other expenses (48,673)   (51,292)   (151,122) (159,885)
Amortization of intangible assets (2,081)   (2,217)   (6,243) (6,651)
Goodwill impairment 0 $ (10,800) 0 $ (83,900) (10,800) (83,895)
Restructuring credit         (3,674) (1,887)
Restructuring credit 538   111   (3,674) (1,887)
Interest expense and other income     (6,146)      
Interest expense, credit loss expense, and other income 85       (491)  
Interest expense, credit loss expense and other income, and loss on investments           (6,697)
Income (loss) before income taxes 2,466   (1,689)   (13,342) (82,875)
Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 86,107   94,295   271,794 295,830
Total segment expenses (33,510) [1]   (36,440) [2]   (112,806) [3] (119,690) [4]
Income (loss) from operations 52,597   57,855   158,988 176,140
Research Segment [Member]            
Segment Reporting Information [Line Items]            
Goodwill impairment         (10,800)  
Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 73,761   78,139   222,944 235,326
Total segment expenses (24,132) [1]   (25,221) [2]   (76,442) (77,539) [4]
Income (loss) from operations 49,629   52,918   146,502 157,787
Consulting Segment [Member]            
Segment Reporting Information [Line Items]            
Goodwill impairment         0  
Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 11,121   15,988   39,160 50,070
Total segment expenses (6,844) [1]   (9,536) [2]   (23,899) [3] (28,591) [4]
Income (loss) from operations 4,277   6,452   15,261 21,479
Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 1,225   168   9,690 10,434
Total segment expenses (2,534) [1]   (1,683) [2]   (12,465) [3] (13,560) [4]
Income (loss) from operations (1,309)   (1,515)   (2,775) (3,126)
Research [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 70,138   72,652   208,736 218,992
Research [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 70,138   72,652   208,736 218,992
Research [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 0   0   0 0
Research [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 0   0   0 0
Consulting [Member]            
Segment Reporting Information [Line Items]            
Total revenues 14,744   21,475   53,368 66,404
Consulting [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 14,744   21,475   53,368 66,404
Consulting [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 3,623   5,487   14,208 16,334
Consulting [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 11,121   15,988   39,160 50,070
Consulting [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 0   0   0 0
Events [Member]            
Segment Reporting Information [Line Items]            
Total revenues 1,225   168   9,690 10,434
Events [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 1,225   168   9,690 10,434
Events [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 0   0   0 0
Events [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 0   0   0 0
Events [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total revenues 1,225   168   9,690 10,434
Compensation Benefits and Related Costs [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (28,355) [1]   (31,577) [2]   (89,989) [3] (94,420) [4]
Compensation Benefits and Related Costs [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (22,032) [1]   (23,230) [2]   (68,016) (69,196) [4]
Compensation Benefits and Related Costs [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (5,125) [1]   (7,085) [2]   (18,144) [3] (21,248) [4]
Compensation Benefits and Related Costs [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,198) [1]   (1,262) [2]   (3,829) [3] (3,976) [4]
Direct Costs of Events [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,222) [1]   (405) [2]   (8,310) [3] (9,378) [4]
Direct Costs of Events [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses 0 [1]   0 [2]   0 0 [4]
Direct Costs of Events [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses 0 [1]   0 [2]   0 [3] 0 [4]
Direct Costs of Events [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,222) [1]   (405) [2]   (8,310) [3] (9,378) [4]
Professional Services [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,425) [1]   (1,961) [2]   (6,748) [3] (7,909) [4]
Professional Services [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,006) [1]   (1,050) [2]   (5,038) (5,398) [4]
Professional Services [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (411) [1]   (960) [2]   (1,702) [3] (2,483) [4]
Professional Services [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (8) [1]   49 [2]   (8) [3] (28) [4]
Billable Expenses [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,273) [1]   (1,471) [2]   (3,987) [3] (4,769) [4]
Billable Expenses [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (65) [1]   (135) [2]   (242) (320) [4]
Billable Expenses [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1,208) [1]   (1,336) [2]   (3,745) [3] (4,449) [4]
Billable Expenses [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses 0 [1]   0 [2]   0 [3] 0 [4]
Travel and Entertainment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (763) [1]   (647) [2]   (2,303) [3] (1,961) [4]
Travel and Entertainment [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (578) [1]   (453) [2]   (1,787) (1,470) [4]
Travel and Entertainment [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (85) [1]   (143) [2]   (256) [3] (385) [4]
Travel and Entertainment [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (100) [1]   (51) [2]   (260) [3] (106) [4]
Software [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (449) [1]   (339) [2]   (1,336) [3] (1,104) [4]
Software [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (433) [1]   (329) [2]   (1,288) (1,060) [4]
Software [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (14) [1]   0 [2]   (37) [3] 0 [4]
Software [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (2) [1]   (10) [2]   (11) [3] (44) [4]
Other Segment Expenses [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (23) [1],[5]   (40) [2],[6]   (133) [3],[7] (149) [4],[8]
Other Segment Expenses [Member] | Research Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (18) [1],[5]   (24) [2],[6]   (71) (95) [4],[8]
Other Segment Expenses [Member] | Consulting Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses (1) [1],[5]   (12) [2],[6]   (15) [3],[7] (26) [4],[8]
Other Segment Expenses [Member] | Events Segment [Member] | Operating Segments [Member]            
Segment Reporting Information [Line Items]            
Total segment expenses $ (4) [1],[5]   $ (4) [2],[6]   $ (47) [3],[7] $ (28) [4],[8]
[1] The significant expense categories and amounts align with the segment-level information that is regularly provided to the chief operating decision maker.
[2] The significant expense categories and amounts align with the segment-level information that is regularly provided to the chief operating decision maker.
[3] The significant expense categories and amounts align with the segment-level information that is regularly provided to the chief operating decision maker.
[4] The significant expense categories and amounts align with the segment-level information that is regularly provided to the chief operating decision maker.
[5] Other segment expenses for each reportable segment includes office supplies, maintenance, and training expenses.
[6] Other segment expenses for each reportable segment includes office supplies, maintenance, and training expenses.
[7] Other segment expenses for each reportable segment includes office supplies, maintenance, and training expenses.
[8] Other segment expenses for each reportable segment includes office supplies, maintenance, and training expenses.