Fair Value - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value Of Financial Instruments [Line Items]
Contingent consideration at fair value	$ 10.5	$ 9.0
Minority Interest Ownership Percentage By Noncontrolling Owners	33.00%
Business Acquisition Contingent Consideration Potential Cash Payment	$ 2.5

Fair value, as of the acquisition date, of potential payments under the contingent consideration arrangement including cash and shares.

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+ Details