Exit Activities - Reserve Activity (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
2012 Exit Activity [Member] | Lease Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 0	$ 0.1	$ 0.6	$ 0
Charge	0	0	0.9
Cash Expenditure	(0.1)	(0.5)	(0.3)
2012 Exit Activity [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0	0
Charge	0	0	0.1
Cash Expenditure	0	0	(0.1)
2013 Exit Activity [Member] | Lease Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0.3	1.5	0	0
Charge	0	2.0	0
Cash Expenditure	(1.2)	(0.5)	0
2013 Exit Activity [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	1.3	0	0
Charge	0	1.8	0
Cash Expenditure	(1.3)	(0.5)	0
2014 Exit Activity [Member] | Lease Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0.5	0	0	0
Charge	2.1	0	0
Cash Expenditure	(1.6)	0	0
2014 Exit Activity [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2.3	0	0	0
Charge	7.8	0	0
Cash Expenditure	$ (5.5)	$ 0	$ 0