Segment Information - Results of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012
Segment Reporting Information [Line Items]
Gross revenues	$ 221,974	$ 201,164	$ 432,734	$ 371,672
Inter-segment revenues	(538)	(200)	(1,690)	(1,387)
Consolidated revenues	221,436	200,964	431,044	370,285
Gross profit	22,333	23,098	44,577	41,191
Operating income	8,772	11,200	16,696	17,810
Segment assets	376,074	315,598	376,074	315,598	323,135
Electrical Infrastructure [Member]
Segment Reporting Information [Line Items]
Gross revenues	50,123	43,628	83,393	65,640
Inter-segment revenues	0	0	0	0
Consolidated revenues	50,123	43,628	83,393	65,640
Gross profit	6,629	4,991	11,335	7,776
Operating income	3,696	2,492	6,015	3,221
Segment assets	72,229	59,919	72,229	59,919
Oil Gas & Chemical [Member]
Segment Reporting Information [Line Items]
Gross revenues	66,635	49,750	133,732	95,749
Inter-segment revenues	0	(33)	0	(208)
Consolidated revenues	66,635	49,717	133,732	95,541
Gross profit	8,045	4,936	15,912	9,283
Operating income	3,927	2,410	7,702	3,822
Segment assets	76,044	50,479	76,044	50,479
Storage Solutions [Member]
Segment Reporting Information [Line Items]
Gross revenues	98,183	99,710	203,601	195,632
Inter-segment revenues	(538)	(167)	(1,690)	(1,179)
Consolidated revenues	97,645	99,543	201,911	194,453
Gross profit	7,748	12,689	17,717	23,076
Operating income	1,550	6,547	4,999	10,773
Segment assets	163,906	138,550	163,906	138,550
Industrial [Member]
Segment Reporting Information [Line Items]
Gross revenues	7,033	8,076	12,008	14,651
Inter-segment revenues	0	0	0	0
Consolidated revenues	7,033	8,076	12,008	14,651
Gross profit	(89)	482	(387)	1,056
Operating income	(401)	(249)	(2,020)	(6)
Segment assets	14,555	18,904	14,555	18,904
All Other Segments [Member]
Segment Reporting Information [Line Items]
Segment assets	$ 49,340	$ 47,746	$ 49,340	$ 47,746