Summary of Acquisition Location (Detail)	3 Months Ended			9 Months Ended
	Sep. 30, 2012 Entity	Jun. 30, 2012 Entity	Mar. 31, 2012 Entity	Sep. 30, 2012 Entity
Business Acquisition [Line Items]
Number of acquisitions completed	12	8	11	31
United States
Business Acquisition [Line Items]
Number of acquisitions completed				12
Argentina
Business Acquisition [Line Items]
Number of acquisitions completed				1
Brazil
Business Acquisition [Line Items]
Number of acquisitions completed				1
Chile
Business Acquisition [Line Items]
Number of acquisitions completed				2
Japan
Business Acquisition [Line Items]
Number of acquisitions completed				1
Mexico
Business Acquisition [Line Items]
Number of acquisitions completed				2
Portugal
Business Acquisition [Line Items]
Number of acquisitions completed				1
Romania
Business Acquisition [Line Items]
Number of acquisitions completed				2
Spain
Business Acquisition [Line Items]
Number of acquisitions completed				6
United Kingdom
Business Acquisition [Line Items]
Number of acquisitions completed				3