Other Financial Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2018
Accrued expenses and other current liabilities
Accrued salaries and benefits	$ 851,100		$ 1,035,900
Accrued contract costs	880,700		861,000
Other accrued expenses	426,100		370,100
Total accrued expenses	2,157,870		2,267,046
Accounts receivable-net	3,373,361		3,307,851
Restructuring costs	79,170
Accrued restructuring expenses	29,000
Severance expense		$ 26,700
Severance and personnel costs
Accrued expenses and other current liabilities
Restructuring costs	56,900
Real estate costs
Accrued expenses and other current liabilities
Restructuring costs	22,300
Accelerated recovery of pension entitlement
Accrued expenses and other current liabilities
Accounts receivable-net	50,000
Professional liability accrual
Accrued expenses and other current liabilities
Accrued contract costs	$ 473,700		$ 519,500