Business Overview - Revenues by Customer (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Concentration Risk [Line Items]
Revenue	$ 152,801	$ 57,852
Department of Homeland Security
Concentration Risk [Line Items]
Revenue	91,328	172
Department of Veterans Affairs
Concentration Risk [Line Items]
Revenue	28,193	27,642
Department of Health and Human Services
Concentration Risk [Line Items]
Revenue	23,126	20,163
Department of Defense
Concentration Risk [Line Items]
Revenue	8,495	6,980
Other customers with less than 10% share of total revenue
Concentration Risk [Line Items]
Revenue	1,659	2,895
Revenue from Contract with Customer | Customer concentration
Concentration Risk [Line Items]
Revenue	$ 152,801	$ 57,852
Percent of total revenue	100.00%	100.00%
Revenue from Contract with Customer | Customer concentration | Department of Homeland Security
Concentration Risk [Line Items]
Revenue	$ 91,328	$ 172
Percent of total revenue	59.80%	0.30%
Revenue from Contract with Customer | Customer concentration | Department of Veterans Affairs
Concentration Risk [Line Items]
Revenue	$ 28,193	$ 27,642
Percent of total revenue	18.50%	47.80%
Revenue from Contract with Customer | Customer concentration | Department of Health and Human Services
Concentration Risk [Line Items]
Revenue	$ 23,126	$ 20,163
Percent of total revenue	15.10%	34.90%
Revenue from Contract with Customer | Customer concentration | Department of Defense
Concentration Risk [Line Items]
Revenue	$ 8,495	$ 6,980
Percent of total revenue	5.60%	12.00%
Revenue from Contract with Customer | Customer concentration | Other customers with less than 10% share of total revenue
Concentration Risk [Line Items]
Revenue	$ 1,659	$ 2,895
Percent of total revenue	1.00%	5.00%