Uncompleted Contracts - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified				3 Months Ended	6 Months Ended
	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2012 S.M. Electric Company	Dec. 31, 2012 Western Canada Aboveground Storage Tank Project	Dec. 31, 2012 Western Canada Aboveground Storage Tank Project
Customer Contracts [Line Items]
Billings in accounts receivable to be collected within one year	$ 23.3	$ 22.3
Contract retentions collectible beyond one year	2.9	1.2
Estimate of the remaining amount to be collected			0.7
Additional claim for amounts due under related contract			2.9
Decrease in operating income due to change in estimate on project				3.3	3.0
Decrease in net income due to change in estimate on project				2.1	2.0
Decrease in diluted earnings per common share due to change in estimate on project				$ 0.08	$ 0.07
Accrued loss included in billings in excess of costs				$ 1.4	$ 1.4