Discontinued Operations, Goodwill, and Intangible Assets (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 28, 2022	Dec. 31, 2021	Mar. 31, 2021	Mar. 31, 2022	Sep. 30, 2021
Summary of financial information of the Disposal Group is as follows:
Long-term liabilities held for sale		$ 7,565			$ 11,095
Held for sale
Summary of financial information of the Disposal Group
Contingent consideration, prior work claims				$ 40,000
Summary of financial information of the Disposal Group is as follows:
Cash and cash equivalents		9,000			5,600
Receivables and contract assets		60,000			90,300
Other		38,800			43,500
Current assets held for sale		107,800			139,400
Property and equipment, net		53,300			52,900
Other		18,100			18,500
Write-down of assets to fair value less cost to sell		(71,400)			(71,400)
Accounts payable and accrued expenses		83,700			88,500
Other		4,900			5,500
Current liabilities held for sale		88,600			94,000
Long-term liabilities held for sale		7,600			$ 11,100
Held for sale | Power construction business
Summary of financial information of the Disposal Group
Pre-tax gain (loss)		$ (17,300)
Held for sale | Civil infrastructure construction business
Summary of financial information of the Disposal Group
Pre-tax gain (loss)			$ (32,800)
Held for sale | Graham Maintenance Services
Summary of financial information of the Disposal Group
Cash, debt and working capital adjustments	$ 14,000