Annual report pursuant to Section 13 and 15(d)

Revenue recognition - Disaggregation of Revenue (Details)

v3.20.2
Revenue recognition - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Disaggregation of Revenue [Line Items]                      
Revenue $ 923,836 $ 901,337 $ 818,135 $ 818,229 $ 754,966 $ 730,710 $ 736,520 $ 664,619 $ 3,461,537 $ 2,886,815 $ 2,392,236
Total U.S. state government agencies                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,344,227 1,166,937  
New York State government agencies                      
Disaggregation of Revenue [Line Items]                      
Revenue                 355,282 362,724  
Other U.S. state government agencies                      
Disaggregation of Revenue [Line Items]                      
Revenue                 988,945 804,213  
United States Federal Government agencies                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,559,165 1,040,980  
International government agencies                      
Disaggregation of Revenue [Line Items]                      
Revenue                 467,185 558,599  
Other, including local municipalities and commercial customers                      
Disaggregation of Revenue [Line Items]                      
Revenue                 90,960 120,299  
Performance-based                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,109,153 1,193,075  
Cost-plus                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,578,912 1,088,541  
Fixed price                      
Disaggregation of Revenue [Line Items]                      
Revenue                 471,505 441,146  
Time and materials                      
Disaggregation of Revenue [Line Items]                      
Revenue                 301,967 164,053  
U.S. Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,329,274 1,176,488  
U.S. Federal Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,633,337 1,111,197  
Outside the U.S.                      
Disaggregation of Revenue [Line Items]                      
Revenue                 498,926 599,130  
Program administration | U.S. Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,008,591 883,772  
Program administration | U.S. Federal Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,288,741 779,573  
Program administration | Outside the U.S.                      
Disaggregation of Revenue [Line Items]                      
Revenue                 66,002 63,734  
Assessments and appeals | U.S. Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 141,446 136,109  
Assessments and appeals | U.S. Federal Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 175,337 171,282  
Assessments and appeals | Outside the U.S.                      
Disaggregation of Revenue [Line Items]                      
Revenue                 218,704 252,447  
Workforce and children services | U.S. Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 127,595 100,454  
Workforce and children services | Outside the U.S.                      
Disaggregation of Revenue [Line Items]                      
Revenue                 206,657 272,801  
Other | U.S. Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 51,642 56,153  
Other | Outside the U.S.                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,563 10,148  
Technology solutions | U.S. Federal Services                      
Disaggregation of Revenue [Line Items]                      
Revenue                 $ 169,259 $ 160,342