Operating Results of Discontinued Operations (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Discontinued Operations [Line Items]
Income tax benefit	$ (0.2)	$ 0.7	$ (0.2)	$ 0.6
Federal Signal Technologies
Discontinued Operations [Line Items]
Net sales		33.6		62.1
Interest allocated to discontinued operations		2.2		3.1
Other costs and expenses		35.4		66.8
Loss before income taxes		(4.0)		(7.8)
Income tax benefit		0.7		0.6
Loss from discontinued operations		$ (3.3)		$ (7.2)