Segment Information - Results of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012	Jun. 30, 2012
Segment Reporting Information [Line Items]
Gross revenues	$ 226,388	$ 184,628	$ 659,122	$ 556,300
Inter-segment revenues	418	729	2,108	2,116
Consolidated revenues	225,970	183,899	657,014	554,184
Gross profit	23,126	19,771	67,703	60,962
Operating income	8,431	7,415	25,127	25,225
Segment assets	379,175	315,776	379,175	315,776	323,135
Electrical Infrastructure [Member]
Segment Reporting Information [Line Items]
Gross revenues	41,709	37,621	125,102	103,261
Inter-segment revenues	0	0	0	0
Consolidated revenues	41,709	37,621	125,102	103,261
Gross profit	4,994	4,809	16,329	12,585
Operating income	2,424	2,540	8,439	5,761
Segment assets	58,640	53,961	58,640	53,961
Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	73,638	55,569	207,370	151,318
Inter-segment revenues	44	0	44	208
Consolidated revenues	73,594	55,569	207,326	151,110
Gross profit	8,016	5,015	23,928	14,298
Operating income	3,285	1,922	10,987	5,744
Segment assets	84,499	63,222	84,499	63,222
Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	95,200	88,326	298,801	283,958
Inter-segment revenues	374	729	2,064	1,908
Consolidated revenues	94,826	87,597	296,737	282,050
Gross profit	8,828	9,999	26,545	33,075
Operating income	2,447	3,745	7,446	14,518
Segment assets	155,739	131,673	155,739	131,673
Industrial [Member]
Segment Reporting Information [Line Items]
Gross revenues	15,841	3,112	27,849	17,763
Inter-segment revenues	0	0	0	0
Consolidated revenues	15,841	3,112	27,849	17,763
Gross profit	1,288	(52)	901	1,004
Operating income	275	(792)	(1,745)	(798)
Segment assets	23,683	13,744	23,683	13,744
All Other Segments [Member]
Segment Reporting Information [Line Items]
Segment assets	$ 56,614	$ 53,176	$ 56,614	$ 53,176

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Concepts (CON)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of revenue from transactions with other operating segments of the same entity.

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Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

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