Uncompleted Contracts - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013
Customer Contracts [Line Items]
Contract Receivable Retainage, Due in Next Twelve Months	$ 24.9		$ 24.9		$ 19.9
Contract Receivable Retainage, Due after Next Twelve Months	3.7		3.7		3.1
Change In Accounting Estimate, Financial Effect, Operating Income	4.4	3.3	4.0	3.0
S.M. Electric Company
Customer Contracts [Line Items]
Estimate of the remaining amount to be collected	0.7		0.7
Contract Receivable	$ 2.9		$ 2.9