Goodwill and Other Intangible Assets - Summary of Goodwill by Segment and Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 244,994	$ 247,211
Translation adjustments	(2,845)	(2,217)
Goodwill, Ending Balance	242,149	244,994
Research Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	236,770	238,913
Translation adjustments	(2,750)	(2,143)
Goodwill, Ending Balance	234,020	236,770
Consulting Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	8,224	8,298
Translation adjustments	(95)	(74)
Goodwill, Ending Balance	$ 8,129	$ 8,224