Summary of Contingent Consideration by Acquisition (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jul. 18, 2011
Business Acquisition, Contingent Consideration [Line Items]
Maximum amount payable	$ 21,737	$ 22,697
Amount paid		281
Expense (income) recognized for changes in fair value	(5,657)	510
Amount outstanding	108	5,765
RockWest
Business Acquisition, Contingent Consideration [Line Items]
Maximum amount payable		960
Amount paid		281
Expense (income) recognized for changes in fair value		(238)
idOnDemand, Inc.
Business Acquisition, Contingent Consideration [Line Items]
Maximum amount payable	21,000	21,000
Expense (income) recognized for changes in fair value	(5,463)	706
Amount outstanding		5,463
polyright SA
Business Acquisition, Contingent Consideration [Line Items]
Maximum amount payable	737	737
Expense (income) recognized for changes in fair value	(194)	42
Amount outstanding	$ 108	$ 302	$ 3,400