Summary of Acquisition Location (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2011 Year Entity	Mar. 31, 2011 Entity	Jun. 30, 2011 Year Entity
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed	11	9	20
United States
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			10
Argentina
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			1
Brazil
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			1
Canada
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			1
Chile
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			1
Ireland
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			1
Romania
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			3
United Kingdom
Significant Acquisitions and Disposals [Line Items]
Number of acquisitions completed			2