Segment Information - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018
Segment Reporting Information [Line Items]
Gross revenues	$ 319,587	$ 270,675
Revenues	318,511	269,910
Gross profit	23,421	28,891
Operating income	2,220	7,321
Segment assets	587,194		$ 558,033
Electrical Infrastructure [Member]
Segment Reporting Information [Line Items]
Gross revenues	44,701	79,971
Revenues	44,701	79,971
Gross profit	3,383	8,267
Operating income	657	3,577
Segment assets	159,595		161,207
Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	75,562	85,861
Revenues	75,491	85,653
Gross profit	5,625	11,038
Operating income	514	4,134
Segment assets	109,417		111,064
Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	113,767	71,572
Revenues	112,762	71,015
Gross profit	9,553	7,540
Operating income	285	(75)
Segment assets	163,125		149,695
Industrial [Member]
Segment Reporting Information [Line Items]
Gross revenues	85,557	33,271
Revenues	85,557	33,271
Gross profit	4,860	2,046
Operating income	764	(315)
Segment assets	61,080		58,816
Other Segments [Member]
Segment Reporting Information [Line Items]
Segment assets	93,977		$ 77,251
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Gross revenues	1,076	765
Intersegment Eliminations [Member] \| Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	71	208
Intersegment Eliminations [Member] \| Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	$ 1,005	$ 557

Gross revenues before intersegment eliminations

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