Segment Information - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Segment Reporting Information [Line Items]
Gross revenues	$ 342,277	$ 283,741	$ 661,864	$ 554,416
Revenues	340,568	282,911	659,079	552,821
Gross profit	27,886	26,703	51,307	55,594
Operating income	5,527	5,174	7,747	12,495
Segment assets	569,552		569,552		$ 558,033
Electrical Infrastructure [Member]
Segment Reporting Information [Line Items]
Gross revenues	58,173	64,852	102,874	144,823
Revenues	58,173	64,852	102,874	144,823
Gross profit	3,562	5,541	6,945	13,808
Operating income	438	1,079	1,095	4,656
Segment assets	147,246		147,246		161,207
Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	87,521	88,396	163,083	174,257
Revenues	86,287	88,359	161,778	174,012
Gross profit	9,157	11,768	14,782	22,806
Operating income	3,585	5,198	4,099	9,332
Segment assets	96,801		96,801		111,064
Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	126,198	71,233	239,965	142,805
Revenues	125,723	70,441	238,485	141,456
Gross profit	11,147	5,298	20,700	12,838
Operating income	1,356	(2,609)	1,641	(2,684)
Segment assets	176,634		176,634		149,695
Industrial [Member]
Segment Reporting Information [Line Items]
Gross revenues	70,385	59,260	155,942	92,531
Revenues	70,385	59,259	155,942	92,530
Gross profit	4,020	4,096	8,880	6,142
Operating income	148	1,506	912	1,191
Segment assets	61,250		61,250		58,816
Other Segments [Member]
Segment Reporting Information [Line Items]
Segment assets	87,621		87,621		$ 77,251
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Gross revenues	1,709	830	2,785	1,595
Intersegment Eliminations [Member] \| Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	1,234	37	1,305	245
Intersegment Eliminations [Member] \| Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	475	792	1,480	1,349
Intersegment Eliminations [Member] \| Industrial [Member]
Segment Reporting Information [Line Items]
Gross revenues	$ 0	$ 1	$ 0	$ 1

Gross revenues before intersegment eliminations

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