Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Statement of Cash Flows [Abstract]
Bad debt expense			$ 1,216
Deferred financing cost amortization	$ 268	$ 199	198
Depreciation and amortization	29,407	25,468	21,914
Loss (gain) on sale of assets	14,139	69	47
Non-cash compensation	4,372	3,775	3,522
Deferred income taxes	5,185	(31)	11,724
Accounts receivable	2,917	(87,160)	(55,371)
Inventories	(1,142)	(27,760)	(30,517)
Costs and estimated earnings in excess of billings	3,456	(8,688)	(13,451)
Prepaid expenses and other current assets	(7,322)	(18,609)	(9,226)
Other non-current assets	2,067	(3,006)	703
Accounts payable and accrued expenses	(10,047)	67,128	30,623
Billings in excess of costs and estimated earnings	19,051	22,450	6,746
Other non-current liabilities	162	(762)	1,214
Net cash provided by operating activities	153,902	16,262	37,924
Purchases of property and equipment	17,667	29,255	7,401
Proceeds from sale of assets	20,602	219	295
Payments to Acquire Equity Method Investments	(165)	(500)	0
Cash received (paid) in conjunction with business combinations	0	0	(92,463)
Net cash used in investing activities	2,770	(29,536)	(99,569)
Borrowings of debt	2,381,562	1,924,469	1,318,530
Repayments of debt	(2,464,221)	(1,882,148)	(1,278,204)
Finance lease payment	(3,338)	(1,801)	(648)
Payments for Repurchase of Redeemable Noncontrolling Interest	0	0	(1,188)
Distribution to noncontrolling interests	(11,491)	(7,000)	(311)
Purchase of treasury stock	(8,284)	(18,556)	(7,006)
Issuance of shares	22	53	0
Net cash used in financing activities	(105,750)	15,017	31,173
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	50,922	1,743	(30,472)
CASH, CASH EQUIVALENTS and RESTRiCTED CASH, beginning of period	24,848	23,105	53,577
CASH, CASH EQUIVALENTS and RESTRICTED CASH, end of period	75,770	24,848	23,105
Cash paid for interest	2,089	3,068	738
Cash paid for income taxes (net)	12,056	3,953	5,062
Bad debt expense			1,216
Issuance of shares	22	53	0
Cash and cash equivalents	75,770	24,848	23,105
Depreciation and amortization	29,407	25,468	21,914
Loss (gain) on sale of assets	14,139	69	47
Operating income (loss)	159,776	56,008	85,583
Deferred financing cost amortization	268	199	198
Non-cash compensation	4,372	3,775	3,522
Contingent consideration	277	277	211
Net income (loss)	$ 119,787	$ 40,186	$ 68,676
Earnings (loss) per share, basic	$ 4.58	$ 1.45	$ 3.19
Earnings (loss) per share, diluted	$ 4.54	$ 1.44	$ 3.15
Weighted Average Number of Shares Outstanding, Basic	20,196,850	20,667,745	20,790,307
Weighted Average Number of Shares Outstanding, Diluted	20,413,032	20,894,625	21,086,432
Gross profit	$ 444,539	$ 318,930	$ 287,998
Cost of services	1,932,688	1,847,878	1,248,495
Revenues	2,377,227	2,166,808	1,536,493
Provision for income taxes	38,761	12,815	16,231
Selling, general and administrative expenses	298,625	262,714	202,251
Other (income) expense, net	(1,794)	37	(286)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	158,548	53,001	84,907
Cash paid for income taxes (net)	12,056	3,953	5,062
Fair Value of Assets Acquired	4,712	0	$ 0
Trade Accounts Receivable
Statement of Cash Flows [Abstract]
Bad debt expense	(120)	3,141
Bad debt expense	$ (120)	$ 3,141