Stock-based Compensation and Equity Grants - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense			$ 910	$ 790
DLH employees
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized expense for DLH employees			$ 2,633	631
Weighted average period for recognition of compensation expense			4 years 6 months 29 days
DLH employees | Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense			$ 563	263
Non-employee directors | Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of restricted stock units issued (in shares)	63,177	90,000
Number of restricted stocks vested in period (in shares)			90,000
Non-employee directors | Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense			$ 347	$ 527