Business Overview (Details)	3 Months Ended
	Dec. 31, 2019 employee market business_area location	Dec. 31, 2018
Concentration Risk [Line Items]
Number of market focus areas | business_area	3
Number of market leveraging core competencies | market	7
Revenue from Contract with Customer | Customer concentration | Federal Government
Concentration Risk [Line Items]
Concentration risk percentage	98.00%
Revenue from Contract with Customer | Customer concentration | VA
Concentration Risk [Line Items]
Concentration risk percentage	46.00%	68.00%
Revenue from Contract with Customer | Customer concentration | HHS
Concentration Risk [Line Items]
Concentration risk percentage	46.00%	30.00%
U.S.
Concentration Risk [Line Items]
Number of employees | employee	1,950
Number of locations in which entity operates	30
Overseas
Concentration Risk [Line Items]
Number of locations in which entity operates	1