Acquisitions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013
Business Acquisition [Line Items]
Common stock consideration in relation to price protection provision guarantees	$ 3.1		$ 3.9
Initial consideration	26.8	9.1
Contingent consideration payment, due date		Dec. 31, 2017
Contingent consideration cap amount		8.0
Purchase price allocation, identifiable intangible assets	9.4		9.4
Purchase price allocation, goodwill			27.2
Contingent consideration estimated fair value, recorded in Other liabilities	$ 8.2		$ 8.2