Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Results of Operations
Gross revenues									$ 741,588	$ 628,514	$ 553,286
Less: Inter-segment revenues									2,542	1,462	2,472
Revenues	184,862	183,899	200,964	169,321	163,629	136,333	175,252	151,838	739,046	627,052	550,814
Gross profit	18,656	19,771	23,098	18,093	20,874	18,570	19,768	15,702	79,618	74,914	52,922
Operating income (loss)	6,410	7,415	11,200	6,610	9,515	7,640	8,632	5,113	31,635	30,900	7,753
Segment assets	323,135				306,436				323,135	306,436	284,808
Capital expenditures									13,534	10,416	5,302
Depreciation and amortization									11,485	11,067	11,751
Electrical Infrastructure [Member]
Results of Operations
Gross revenues									135,086	151,065	103,015
Less: Inter-segment revenues										7	21
Revenues									135,086	151,058	102,994
Gross profit									16,676	18,337	13,289
Operating income (loss)									7,609	9,111	3,501
Segment assets	51,998				46,411				51,998	46,411	47,456
Capital expenditures									2,581	2,511	266
Depreciation and amortization									1,823	1,613	1,299
Oil Gas & Chemical [Member]
Results of Operations
Gross revenues									206,031	143,753	150,344
Less: Inter-segment revenues									208	399	1,460
Revenues									205,384	143,354	148,884
Gross profit									20,070	13,647	9,121
Operating income (loss)									8,134	3,105	(849)
Segment assets	53,567				42,801				53,567	42,801	43,603
Capital expenditures									2,346	908	335
Depreciation and amortization									2,838	2,490	2,869
Storage Solutions [Member]
Results of Operations
Gross revenues									380,488	299,762	272,305
Less: Inter-segment revenues									2,334	1,056	991
Revenues									378,154	298,706	271,314
Gross profit									42,393	38,779	27,806
Operating income (loss)									17,493	16,612	6,183
Segment assets	150,543				131,050				150,543	131,050	121,919
Capital expenditures									3,929	4,098	1,440
Depreciation and amortization									6,309	6,533	7,220
Industrial [Member]
Results of Operations
Gross revenues									19,983	33,934	27,622
Revenues									19,983	33,934	27,622
Gross profit									479	4,151	2,706
Operating income (loss)									(1,601)	2,072	(1,082)
Segment assets	14,018				19,542				14,018	19,542	11,341
Capital expenditures									741	9
Depreciation and amortization									515	431	363
Other [Member]
Results of Operations
Segment assets	53,009				66,632				53,009	66,632	60,489
Capital expenditures									$ 3,937	$ 2,890	$ 3,231