Changes in Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill, beginning balance	$ 1,600,421	$ 1,452,986
Acquisitions during the period	0	270,631
Foreign exchange impact	97,139	(123,196)
Goodwill, ending balance	1,697,560	1,600,421
Accumulated impairment losses as at January 1	(930,127)	0
Foreign exchange impact	(51,201)	0
Impairment charges recognized during the period	(327,847)	(930,127)
Accumulated impairment losses as at December 31	(1,309,175)	(930,127)
Goodwill beginning balance, net	670,294	1,452,986
Goodwill ending balance, net	$ 388,385	$ 670,294