Reconciliation of Beginning and Ending Liability for Uncertain Tax Provision (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2010
Income Tax Contingency [Line Items]
Liability at beginning and end of year, net	$ 0.8	$ 0.8	$ 0.8
Additions for tax positions of prior years	5.4
Deferred deductions	(4.8)
Liability at end of year, net	$ 1.4	$ 0.8	$ 0.8