Business Combinations - Total Acquisition Consideration and Fair Value of Net Assets Acquired (Details) - USD ($) $ in Thousands	Jun. 07, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net assets acquired
Goodwill		$ 52,758	$ 25,989	$ 25,989
S3
Business Acquisition [Line Items]
Final purchase price for S3	$ 70,115
Net assets acquired
Cash and cash equivalents	3,037
Accounts receivable	13,038
Other current assets	1,418
Total current assets	17,493
Accounts payable and accrued expenses	(4,488)
Payroll liabilities	(3,624)
Long term liabilities	(1,206)
Net working capital	8,175
Equipment and improvements, net	4,605
Net identifiable assets acquired	12,780
Goodwill	26,769
Intangible assets acquired	57,335
Net assets acquired	70,115
S3 | Customer contracts and related customer relationships
Net assets acquired
Intangible assets acquired	28,974
S3 | Trade name
Net assets acquired
Intangible assets acquired	$ 1,592