Segment Information - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	$ 411,755	$ 381,017	$ 815,896	$ 744,402
Revenues before reimbursable expenses	402,505	371,654	798,195	727,615
Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	234,724	224,561	463,507	430,477
Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	177,031	156,456	352,389	313,925
Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	229,122	218,339	453,043	419,898
Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	173,383	153,315	345,152	307,717
Education
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	131,686	125,186	256,702	238,731
Revenues before reimbursable expenses	129,301	122,753	252,049	234,336
Education \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	68,351	65,178	133,009	121,072
Education \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	63,335	60,008	123,693	117,659
Education \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	67,329	63,831	130,873	118,940
Education \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	61,972	58,922	121,176	115,396
Commercial:
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	76,798	60,150	152,602	125,021
Revenues before reimbursable expenses	75,382	58,803	149,834	122,439
Commercial: \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	16,225	20,919	33,317	43,589
Commercial: \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	60,573	39,231	119,285	81,432
Commercial: \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	16,038	20,521	33,041	42,760
Commercial: \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	59,344	38,282	116,793	79,679
Healthcare
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	203,271	195,681	406,592	380,650
Revenues before reimbursable expenses	197,822	190,098	396,312	370,840
Healthcare \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	150,148	138,464	297,181	265,816
Healthcare \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	53,123	57,217	109,411	114,834
Healthcare \| Consulting And Managed Services Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	145,755	133,987	289,129	258,198
Healthcare \| Digital Capability [Member]
Disaggregation of Revenue [Line Items]
Revenues before reimbursable expenses	$ 52,067	$ 56,111	$ 107,183	$ 112,642