Business Overview (Details)	9 Months Ended
	Jun. 30, 2018 employee location	Jun. 30, 2017
Concentration Risk [Line Items]
Business base percentage, prime contracts	99.00%
Business base percentage, subcontracts	1.00%
VA and HSS | Minimum
Concentration Risk [Line Items]
Government contract, term of award	4 months
VA and HSS | Maximum
Concentration Risk [Line Items]
Government contract, term of award	2 years
Customer concentration | HSS
Concentration Risk [Line Items]
Concentration risk percentage	32.00%
Customer concentration | Defense/VA
Concentration Risk [Line Items]
Concentration risk percentage	65.00%
Customer concentration | Public Health/Life Sciences
Concentration Risk [Line Items]
Concentration risk percentage	3.00%
Customer concentration | Public Health/Life Sciences | Time and Materials
Concentration Risk [Line Items]
Concentration risk percentage	97.00%
Customer concentration | Public Health/Life Sciences | Cost Plus Fixed Fee
Concentration Risk [Line Items]
Concentration risk percentage	2.00%
Customer concentration | Public Health/Life Sciences | Firm Fixed Price
Concentration Risk [Line Items]
Concentration risk percentage	1.00%
Customer concentration | Revenue concentration | US Federal Government
Concentration Risk [Line Items]
Concentration risk percentage	100.00%
Customer concentration | Revenue concentration | VA
Concentration Risk [Line Items]
Concentration risk percentage	64.00%	58.00%
Customer concentration | Revenue concentration | HSS
Concentration Risk [Line Items]
Concentration risk percentage	34.00%	32.00%
UNITED STATES
Concentration Risk [Line Items]
Number of employees | employee	1,500
Number of locations in which entity operates | location	30