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Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2019
Revenue, Performance Obligation [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 536,700		$ 536,700
Performance obligations to be recognized as revenue within next twelve months	431,200		431,200
Contract with Customer, Asset and Liability [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts	56,859		56,859		$ 96,083
Change in CIE			(39,224)
Billings on uncompleted contracts in excess of costs and estimated earnings	(100,566)		(100,566)		(105,626)
Change in BIE			5,060
Change in net contract balances			(34,164)
Contract with customer, current liability, net	(43,707)		(43,707)		(9,543)
Contract with Customer, Liability, Revenue Recognized			102,600
Disclosure Customer Contracts Additional Information [Abstract]
Contract Receivable Retainage, Due in Next Twelve Months	39,800		39,800		21,900
Contract Receivable Retainage, Due after Next Twelve Months	5,700		5,700		$ 17,700
Disaggregation of Revenue [Line Items]
Revenue	248,327	$ 358,887	905,101	$ 1,017,966
Fixed-price Contract
Disaggregation of Revenue [Line Items]
Revenue	182,282	183,899	533,375	545,832
Time-and-materials Contract
Disaggregation of Revenue [Line Items]
Revenue	66,045	174,988	371,726	472,134
United States
Disaggregation of Revenue [Line Items]
Revenue	232,606	345,953	838,371	985,603
Canada
Disaggregation of Revenue [Line Items]
Revenue	12,633	10,691	58,506	27,486
Other international
Disaggregation of Revenue [Line Items]
Revenue	$ 3,088	$ 2,243	$ 8,224	$ 4,877