Significant Non-cash Transactions (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Other Significant Noncash Transactions [Line Items]
Common units issued as part of acquisitions' purchase consideration				$ 0	$ 104
Acquisition date fair value of contingent consideration in connection with business combinations				10,315	2,084
Mezzanine Notes net settled with Mezzanine Warrant exercises				0	14
Unsecured notes payable to related and unrelated creditors net settled with Junior Subordinated Notes Warrants				0	2,565
Settlement of warrant liability with equity as a result of Mezzanine Warrant exercise				0	9,253
Preferred return on Class A Units and Redeemable Class A Units	$ 175	$ 209	$ 168
Increase in accrued equity issuance costs				0	760
Conversion of notes payable to related and unrelated creditors to Class A common stock				0	8,054
Redeemable Class A
Other Significant Noncash Transactions [Line Items]
Preferred return on Class A Units and Redeemable Class A Units				0	552
Class A Common Stock
Other Significant Noncash Transactions [Line Items]
Common units issued as part of acquisitions' purchase consideration				225	0
Preferred return on Class A Units and Redeemable Class A Units	$ 0	$ 0	$ 0	0	2,522
2017 Senior Secured Credit Facility | Line of Credit
Other Significant Noncash Transactions [Line Items]
Replacement of Senior Secured Facility				0	87,525
Debt issuance costs financed with proceeds from Senior Secured Credit Facility				0	904
2019 Senior Secured Credit Facility | Line of Credit
Other Significant Noncash Transactions [Line Items]
Replacement of Senior Secured Facility				100,229	0
Debt issuance costs financed with proceeds from Senior Secured Credit Facility				$ 1,271	$ 0