Detail of Certain Balance Sheet Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Detail of Certain Balance Sheet Accounts [Abstract]
Accounts Receivable, Allowance for Credit Loss, Beginning	$ 1,184	$ 868
Addition to costs and expenses	1,864	552
Deductions for uncollectible receivables written off, net of recoveries	(435)	(236)
Accounts Receivable, Allowance for Credit Loss, Ending	2,613	1,184
Accounts payable, trade	93,315	85,276
Accrued compensation and benefits	53,933	42,828
Accrued insurance liabilities	6,254	6,683
Current operating lease liabilities	11,056
Other accrued expenses	22,152	18,122
Accounts payable and accrued expenses	186,710	152,909
Executive Savings Plan assets	766	763
Securities and equity investments	0	408
Other	5,014	3,767
Other non-current assets	$ 5,780	$ 4,938