Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 23,105	$ 53,577
Accounts receivable	286,707	213,016
Accounts and Other Receivables, Net, Current	41,341	40,878
Inventories	68,573	24,889
Costs and estimated earnings in excess of billings	43,389	29,937
Prepaid expenses and other current assets	21,065	9,153
Total current assets	484,180	371,450
Property and equipment, net	35,454	24,589
Goodwill	92,395	53,763
Intangible assets, net	85,619	39,357
Deferred tax assets	19,009	33,803
Operating right of use assets	42,916	31,786
Other non-current assets	7,049	5,780
Total assets	766,622	560,528
Accounts payable and accrued expenses	249,114	186,710
Billings in excess of costs and estimated earnings	62,486	55,739
Total current liabilities	311,600	242,449
Long-term debt	39,746	217
Operating long-term lease liabilities	28,649	20,530
Other non-current liabilities	16,080	12,215
Total liabilities	396,075	275,411
Noncontrolling interest	$ 24,594	$ 1,804
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred stock, value	$ 0	$ 0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares, Issued	22,049,529	22,049,529
Common Stock, Shares, Outstanding	20,732,531	20,762,395
Common stock, value	$ 220	$ 220
Treasury Stock, Shares	1,316,998	1,287,134
Treasury stock, value	$ (29,300)	$ (24,499)
Additional paid-in capital	201,899	200,587
Retained earnings	173,134	107,005
Total stockholders' equity	345,953	283,313
Total liabilities and stockholders' equity	$ 766,622	$ 560,528