Business Acquisitions, Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended
	Mar. 31, 2017	Mar. 31, 2017
Goodwill [Roll Forward]
Gross Goodwill, Beginning of Period	$ 136,913
Goodwill, Impaired, Accumulated Impairment Loss, Beginning of Period	(61,576)
Goodwill, Beginning of Period	75,337
Goodwill, Period Increase (Decrease)	15,717
Gross Goodwill, End of Period	152,630
Goodwill, Impaired, Accumulated Impairment Loss, End of Period	(61,576)
Goodwill	75,337	$ 91,054
Power
Goodwill [Roll Forward]
Gross Goodwill, Beginning of Period	28,506
Goodwill, Impaired, Accumulated Impairment Loss, Beginning of Period	(14,506)
Goodwill, Beginning of Period	14,000
Goodwill, Period Increase (Decrease)	0
Gross Goodwill, End of Period	28,506
Goodwill, Impaired, Accumulated Impairment Loss, End of Period	(14,506)
Goodwill	14,000	14,000
Environmental
Goodwill [Roll Forward]
Gross Goodwill, Beginning of Period	40,889
Goodwill, Impaired, Accumulated Impairment Loss, Beginning of Period	(17,865)
Goodwill, Beginning of Period	23,024
Goodwill, Period Increase (Decrease)	0
Gross Goodwill, End of Period	40,889
Goodwill, Impaired, Accumulated Impairment Loss, End of Period	(17,865)
Goodwill	23,024	23,024
Infrastructure
Goodwill [Roll Forward]
Gross Goodwill, Beginning of Period	7,224
Goodwill, Impaired, Accumulated Impairment Loss, Beginning of Period	(7,224)
Goodwill, Beginning of Period	0
Goodwill, Period Increase (Decrease)	15,717
Gross Goodwill, End of Period	22,941
Goodwill, Impaired, Accumulated Impairment Loss, End of Period	(7,224)
Goodwill	0	15,717
Oil and Gas
Goodwill [Roll Forward]
Gross Goodwill, Beginning of Period	60,294
Goodwill, Impaired, Accumulated Impairment Loss, Beginning of Period	(21,981)
Goodwill, Beginning of Period	38,313
Goodwill, Period Increase (Decrease)	0
Gross Goodwill, End of Period	60,294
Goodwill, Impaired, Accumulated Impairment Loss, End of Period	(21,981)
Goodwill	$ 38,313	$ 38,313