Quarterly report [Sections 13 or 15(d)]

Revenue Recognition - Schedule of Disaggregation of Revenue (Details)

v3.26.1
Revenue Recognition - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]        
Total revenue $ 1,305,967 $ 1,361,786 $ 2,651,013 $ 2,764,461
New York state government agencies        
Disaggregation of Revenue [Line Items]        
Total revenue $ 147,360 $ 155,949 $ 297,481 $ 317,644
New York state government agencies | Revenue Benchmark | Customer Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 11.30% 11.50% 11.20% 11.50%
Other U.S. state government agencies        
Disaggregation of Revenue [Line Items]        
Total revenue $ 272,787 $ 287,184 $ 541,259 $ 578,251
Other U.S. state government agencies | Revenue Benchmark | Customer Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 20.90% 21.10% 20.40% 20.90%
Total U.S. state government agencies        
Disaggregation of Revenue [Line Items]        
Total revenue $ 420,147 $ 443,133 $ 838,740 $ 895,895
U.S. federal government agencies        
Disaggregation of Revenue [Line Items]        
Total revenue $ 734,888 $ 759,583 $ 1,502,691 $ 1,524,020
U.S. federal government agencies | Revenue Benchmark | Customer Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 56.30% 55.80% 56.70% 55.10%
International government agencies        
Disaggregation of Revenue [Line Items]        
Total revenue $ 134,847 $ 138,724 $ 275,859 $ 305,590
International government agencies | Revenue Benchmark | Customer Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 10.30% 10.20% 10.40% 11.10%
Other, including local municipalities and commercial customers        
Disaggregation of Revenue [Line Items]        
Total revenue $ 16,085 $ 20,346 $ 33,723 $ 38,956
Other, including local municipalities and commercial customers | Revenue Benchmark | Customer Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 1.20% 1.50% 1.30% 1.40%
Performance-based        
Disaggregation of Revenue [Line Items]        
Total revenue $ 733,098 $ 714,406 $ 1,453,759 $ 1,432,177
Performance-based | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 56.10% 52.50% 54.80% 51.80%
Cost-plus        
Disaggregation of Revenue [Line Items]        
Total revenue $ 343,924 $ 334,499 $ 730,312 $ 718,926
Cost-plus | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 26.30% 24.60% 27.50% 26.00%
Fixed price        
Disaggregation of Revenue [Line Items]        
Total revenue $ 165,608 $ 185,009 $ 334,127 $ 359,688
Fixed price | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 12.70% 13.60% 12.60% 13.00%
Time and materials        
Disaggregation of Revenue [Line Items]        
Total revenue $ 63,337 $ 127,872 $ 132,815 $ 253,670
Time and materials | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 4.80% 9.40% 5.00% 9.20%
Program Operations        
Disaggregation of Revenue [Line Items]        
Total revenue $ 644,892 $ 690,772 $ 1,321,299 $ 1,418,739
Program Operations | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 49.40% 50.70% 49.80% 51.30%
Clinical Services        
Disaggregation of Revenue [Line Items]        
Total revenue $ 530,808 $ 503,963 $ 1,054,527 $ 975,489
Clinical Services | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 40.60% 37.00% 39.80% 35.30%
Employment & Other        
Disaggregation of Revenue [Line Items]        
Total revenue $ 60,008 $ 78,989 $ 130,173 $ 192,607
Employment & Other | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 4.60% 5.80% 4.90% 7.00%
Technology Solutions        
Disaggregation of Revenue [Line Items]        
Total revenue $ 70,259 $ 88,062 $ 145,014 $ 177,626
Technology Solutions | Revenue Benchmark | Contract Concentration Risk        
Disaggregation of Revenue [Line Items]        
Total revenue (as a percent) 5.40% 6.50% 5.50% 6.40%