| Segment Information | 
Segment Information The table below provides certain financial information for each of our business segments.  
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|   |   | Three Months Ended March 31, |   | Six Months Ended March 31, |  
| (dollars in thousands) |   | 2018 |   | % (1) |   | 2017 |   | % (1) |   | 2018 |   | % (1) |   | 2017 |   | % (1) |  
| Revenue: |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |  
| Health Services |   | $ | 365,633 | 
 |   | 100 | % |   | $ | 348,994 | 
 |   | 100 | % |   | $ | 717,723 | 
 |   | 100 | % |   | $ | 689,723 | 
 |   | 100 | % |  
| U.S. Federal Services |   | 116,327 | 
 |   | 100 | % |   | 145,370 | 
 |   | 100 | % |   | 249,310 | 
 |   | 100 | % |   | 286,668 | 
 |   | 100 | % |  
| Human Services |   | 130,827 | 
 |   | 100 | % |   | 127,683 | 
 |   | 100 | % |   | 268,902 | 
 |   | 100 | % |   | 253,220 | 
 |   | 100 | % |  
| Total |   | $ | 612,787 | 
 |   | 100 | % |   | $ | 622,047 | 
 |   | 100 | % |   | $ | 1,235,935 | 
 |   | 100 | % |   | $ | 1,229,611 | 
 |   | 100 | % |  
| Gross profit: |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |  
| Health Services |   | $ | 98,207 | 
 |   | 26.9 | % |   | $ | 86,454 | 
 |   | 24.8 | % |   | $ | 189,263 | 
 |   | 26.4 | % |   | $ | 164,688 | 
 |   | 23.9 | % |  
| U.S. Federal Services |   | 27,374 | 
 |   | 23.5 | % |   | 36,571 | 
 |   | 25.2 | % |   | 60,732 | 
 |   | 24.4 | % |   | 74,147 | 
 |   | 25.9 | % |  
| Human Services |   | 23,222 | 
 |   | 17.8 | % |   | 29,292 | 
 |   | 22.9 | % |   | 50,768 | 
 |   | 18.9 | % |   | 58,300 | 
 |   | 23.0 | % |  
| Total |   | $ | 148,803 | 
 |   | 24.3 | % |   | $ | 152,317 | 
 |   | 24.5 | % |   | $ | 300,763 | 
 |   | 24.3 | % |   | $ | 297,135 | 
 |   | 24.2 | % |  
| Selling, general and administrative expense: |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |  
| Health Services |   | $ | 35,190 | 
 |   | 9.6 | % |   | $ | 29,914 | 
 |   | 8.6 | % |   | $ | 68,606 | 
 |   | 9.6 | % |   | $ | 58,021 | 
 |   | 8.4 | % |  
| U.S. Federal Services |   | 17,540 | 
 |   | 15.1 | % |   | 18,927 | 
 |   | 13.0 | % |   | 34,188 | 
 |   | 13.7 | % |   | 38,622 | 
 |   | 13.5 | % |  
| Human Services |   | 19,829 | 
 |   | 15.2 | % |   | 19,663 | 
 |   | 15.4 | % |   | 39,324 | 
 |   | 14.6 | % |   | 36,902 | 
 |   | 14.6 | % |  
| Other (2)  |   | — | 
 |   | NM | 
 |   | 92 | 
 |   | NM | 
 |   | — | 
 |   | NM | 
 |   | 449 | 
 |   | NM | 
 |  
| Total |   | $ | 72,559 | 
 |   | 11.8 | % |   | $ | 68,596 | 
 |   | 11.0 | % |   | $ | 142,118 | 
 |   | 11.5 | % |   | $ | 133,994 | 
 |   | 10.9 | % |  
| Operating income: |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |   |   | 
 |  
| Health Services |   | $ | 63,017 | 
 |   | 17.2 | % |   | $ | 56,540 | 
 |   | 16.2 | % |   | $ | 120,657 | 
 |   | 16.8 | % |   | $ | 106,667 | 
 |   | 15.5 | % |  
| U.S. Federal Services |   | 9,834 | 
 |   | 8.5 | % |   | 17,644 | 
 |   | 12.1 | % |   | 26,544 | 
 |   | 10.6 | % |   | 35,525 | 
 |   | 12.4 | % |  
| Human Services |   | 3,393 | 
 |   | 2.6 | % |   | 9,629 | 
 |   | 7.5 | % |   | 11,444 | 
 |   | 4.3 | % |   | 21,398 | 
 |   | 8.5 | % |  
| Amortization of intangible assets |   | (2,603 | ) |   | NM | 
 |   | (3,386 | ) |   | NM | 
 |   | (5,321 | ) |   | NM | 
 |   | (6,788 | ) |   | NM | 
 |  
| Restructuring costs (3) |   | (2,320 | ) |   | NM | 
 |   | — | 
 |   | NM | 
 |   | (2,320 | ) |   | NM | 
 |   | (2,242 | ) |   | NM | 
 |  
| Other (2) |   | — | 
 |   | NM | 
 |   | (92 | ) |   | NM | 
 |   | — | 
 |   | NM | 
 |   | (449 | ) |   | NM | 
 |  
| Total |   | $ | 71,321 | 
 |   | 11.6 | % |   | $ | 80,335 | 
 |   | 12.9 | % |   | $ | 151,004 | 
 |   | 12.2 | % |   | $ | 154,111 | 
 |   | 12.5 | % | (1)    Percentage of respective segment revenue. Percentages not considered meaningful are marked “NM.” 
|  |  |  
| 
(2) 
 | 
Other costs and credits relate to SG&A balances that do not relate directly to segment business activities. During the six months ended March 31, 2017 we incurred $0.4 million of legal costs pertaining to a matter which occurred in fiscal year 2009. 
 |  
|  |  |  
| (3) | During fiscal years 2018 and 2017, we incurred costs in restructuring our United Kingdom Human Services business. See "Note 5. Supplemental disclosures" for more information. |  |