Uncompleted Contracts - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2015
Customer Contracts [Line Items]
Contract Receivable Retainage, Due in Next Twelve Months	$ 24.4		$ 24.4		$ 25.2
Contract Receivable Retainage, Due after Next Twelve Months	5.6		5.6		$ 2.8
Change In Accounting Estimate, Financial Effect, Operating Income	$ 1.6	$ 28.5	$ 7.1	$ 54.7
Change in Accounting Estimate, Financial Effect, Net Income	0.5	9.7	2.5	18.7