Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 232,599	$ 227,614	$ 222,738	$ 222,111	$ 214,730	$ 192,820	$ 184,136	$ 169,341	$ 905,062	$ 761,027	$ 612,133
Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									900,310	756,486	607,101
Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									4,752	4,541	5,032
Professional Services
Disaggregation of Revenue [Line Items]
Revenues									892,647	745,166	593,565
Professional Services | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									892,647	745,166	593,565
Professional Services | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Professional Services | Time and materials contracts
Disaggregation of Revenue [Line Items]
Revenues									696,040	577,674	436,466
Professional Services | Time and materials contracts | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									696,040	577,674	436,466
Professional Services | Time and materials contracts | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Professional Services | Fixed fee percent complete contracts
Disaggregation of Revenue [Line Items]
Revenues									52,183	49,117	51,752
Professional Services | Fixed fee percent complete contracts | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									52,183	49,117	51,752
Professional Services | Fixed fee percent complete contracts | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Professional Services | Fixed fee contracts
Disaggregation of Revenue [Line Items]
Revenues									135,053	107,698	95,237
Professional Services | Fixed fee contracts | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									135,053	107,698	95,237
Professional Services | Fixed fee contracts | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Professional Services | Reimbursable expenses
Disaggregation of Revenue [Line Items]
Revenues									9,371	10,677	10,110
Professional Services | Reimbursable expenses | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									9,371	10,677	10,110
Professional Services | Reimbursable expenses | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Other Services
Disaggregation of Revenue [Line Items]
Revenues									9,774	13,556	16,018
Other Services | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									7,663	11,320	13,536
Other Services | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									2,111	2,236	2,482
Total services
Disaggregation of Revenue [Line Items]
Revenues									902,421	758,722	609,583
Total services | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									900,310	756,486	607,101
Total services | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									2,111	2,236	2,482
Software and hardware
Disaggregation of Revenue [Line Items]
Revenues									2,641	2,305	2,550
Software and hardware | Transferred Over Time
Disaggregation of Revenue [Line Items]
Revenues									0	0	0
Software and hardware | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues									2,641	2,305	2,550
United States
Disaggregation of Revenue [Line Items]
Revenues									875,298	738,298	599,236
Other countries
Disaggregation of Revenue [Line Items]
Revenues									$ 29,764	$ 22,729	$ 12,897