Business Overview (Details)	6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Concentration Risk [Line Items]
Minimum period for which entity has provided professional services to the U.S. Government (years)	25 years
Number of employees (employee)	1,200
Minimum number of locations in which entity operates (location)	25
Number of broad integrated revenue streams	2
US Government [Member] | Revenue concentration | Customer concentration
Concentration Risk [Line Items]
Concentration risk percentage (percent)	100.00%	100.00%
DVA | Revenue concentration | Customer concentration
Concentration Risk [Line Items]
Concentration risk percentage (percent)	96.00%	97.00%
DVA | Minimum
Concentration Risk [Line Items]
Term of government contract	2 years
DVA | Maximum
Concentration Risk [Line Items]
Term of government contract	4 years