Goodwill And Other Intangible Assets (Rollforward of Intangible Assets, Including Goodwill) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Goodwill and Other Intangible Assets [Roll Forward]
Goodwill, beginning balance	$ 714,760,000		$ 525,600,000
Other intangible assets, non-amortizing, beginning balance	66,200,000		34,900,000
Other intangible assets, amortizing, beginning balance	44,500,000	[1]	36,000,000
Goodwill and other intangible assets, beginning balance	825,467,000		596,500,000
Additions from new business combinations, goodwill	80,200,000		177,400,000
Additions from new business combinations, non-amortizing intangible assets	0		31,300,000
Additions from new business combinations, amortizing intangible assets	38,600,000		22,400,000
Additions from new business combinations, goodwill and other intangible assets	118,800,000		231,100,000
Accruals of acquisition-related contingent consideration	25,500,000	[2]	11,800,000	[2]
Amortization expense	(12,200,000)		(13,900,000)
Currency translation, goodwill	(200,000)
Currency translation, non-amortizing intangible assets	0
Currency translation, amortizing intangible assets	0
Currency translation, goodwill and other intangible assets	(200,000)
Goodwill, ending balance	820,341,000		714,760,000
Other intangible assets, non-amortizing, ending balance	66,200,000		66,200,000
Other intangible assets, amortizing, ending balance	70,900,000	[1]	44,500,000	[1]
Goodwill and other intangible assets, ending balance	957,441,000		825,467,000
Earn-out Arrangements [Member]
Goodwill and Other Intangible Assets [Roll Forward]
Accruals of acquisition-related contingent consideration	$ 25,500,000	[2]	$ 11,800,000	[2]

[1] Consists principally of customer relationships, backlog, trade names and non-compete agreements with finite lives.

[2] Represents contingent consideration for acquisitions prior to January 1, 2009, which is only accrued as earned, in accordance with U.S. GAAP.