Annual report pursuant to Section 13 and 15(d)

Business segments - Schedule of Segment Reporting Results By Segment (Details)

v3.20.2
Business segments - Schedule of Segment Reporting Results By Segment (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Sep. 30, 2020
USD ($)
Jun. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Sep. 30, 2019
USD ($)
Jun. 30, 2019
USD ($)
Mar. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Sep. 30, 2020
USD ($)
segment
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Segment Reporting [Abstract]                      
Number of business segments | segment                 3    
Financial information for each of the Company's business segments                      
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
Gross profit 196,851 185,603 153,098 175,450 168,250 174,247 169,422 159,265 711,002 671,184 594,385
Selling, general and administrative expense                 387,090 321,023 285,241
Operating income 84,523 87,309 37,311 79,135 77,576 83,594 81,801 74,136 288,278 317,107 295,483
Amortization of intangible assets                 (35,634) (33,054) (10,308)
Gain on sale of a business                 1,718 0 0
Depreciation and amortization                 64,527 52,404 51,884
Segment Reconciling Items                      
Financial information for each of the Company's business segments                      
Selling, general and administrative expense                 4,358 2,676 2,844
Amortization of intangible assets (8,900) (8,712) (8,934) (9,088) (9,028) (9,049) (9,519) (5,458) (35,634) (33,054) (10,308)
Restructuring costs                 0 0 (3,353)
Acquisition-related expenses (459) (150) (3,377) (635) 0 0 0 (2,691) (4,621) (2,691) (947)
Gain on sale of a business 12 1,706 0 0         1,718 0 0
Other                 263 15 (1,897)
U.S. Services                      
Financial information for each of the Company's business segments                      
Revenue                 1,329,274 1,176,488  
U.S. Services | Operating segments                      
Financial information for each of the Company's business segments                      
Revenue 371,345 336,950 308,698 312,281 300,406 291,132 290,737 294,213 1,329,274 1,176,488 1,213,911
Gross profit 92,199 93,029 85,454 89,590 83,154 86,664 86,260 88,031 360,272 344,109 359,624
Selling, general and administrative expense                 132,489 123,275 140,990
Operating income 62,343 61,033 46,215 58,192 53,832 54,250 56,860 55,892 227,783 220,834 218,634
Depreciation and amortization                 20,951 18,466 20,963
U.S. Federal Services                      
Financial information for each of the Company's business segments                      
Revenue                 1,633,337 1,111,197  
U.S. Federal Services | Operating segments                      
Financial information for each of the Company's business segments                      
Revenue 423,232 450,143 393,391 366,571 312,179 292,295 289,736 216,987 1,633,337 1,111,197 478,911
Gross profit 86,423 84,723 76,958 70,821 66,586 66,803 60,696 47,985 318,925 242,070 126,698
Selling, general and administrative expense                 186,023 126,128 69,312
Operating income 31,855 39,233 30,232 31,582 31,090 33,907 29,592 21,353 132,902 115,942 57,386
Depreciation and amortization                 25,153 16,802 8,478
Outside the U.S.                      
Financial information for each of the Company's business segments                      
Revenue                 498,926 599,130  
Outside the U.S. | Operating segments                      
Financial information for each of the Company's business segments                      
Revenue 129,259 114,244 116,046 139,377 142,381 147,283 156,047 153,419 498,926 599,130 699,414
Gross profit 18,229 7,851 (9,314) 15,039 18,510 20,780 22,466 23,249 31,805 85,005 108,063
Selling, general and administrative expense                 65,938 68,944 72,095
Operating income $ (584) $ (5,817) $ (26,718) $ (1,014) $ 2,157 $ 4,989 $ 4,474 $ 4,441 (34,133) 16,061 35,968
Depreciation and amortization                 $ 18,423 $ 17,136 $ 22,443