Goodwill And Other Intangible Assets (Rollforward Of Goodwill And Other Intangible Assets) (Details) (USD $)	12 Months Ended						12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011 Indefinite Lived Intangible Assets Excluding Goodwill [Member]	Dec. 31, 2009 Indefinite Lived Intangible Assets Excluding Goodwill [Member]	Dec. 31, 2011 Goodwill [Member]		Dec. 31, 2010 Goodwill [Member]		Dec. 31, 2011 Finite Lived Intangible Assets [Member]	Dec. 31, 2010 Finite Lived Intangible Assets [Member]
Goodwill And Other Intangible Assets [Line Items]
Goodwill, Beginning Balance	$ 613,369,000						$ 613,400,000		$ 504,200,000
Intangible assets, non-amortizing, Beginning Balance	655,300,000				41,900,000	41,900,000
Other intangible assets, amortizing, Beginning Balance	36,300,000	[1]									36,300,000	49,300,000
Goodwill and other intangible assets, Beginning Balance	691,600,000		595,400,000
Goodwill, Additions from new business combinations							170,100,000
Other intangible assets, non-amortizing, Additions from new business combinations					31,300,000
Other intangible assets, amortizing, Additions from new business combinations											22,400,000
Total, Additions from new business combinations	223,800,000
Accruals of acquisition-related contingent consideration	24,400,000	[2]	41,300,000	[2]			24,400,000	[2]	41,300,000	[2]
Settlement of multiple year earn-out (See Note 3)			67,000,000						67,000,000
Amortization expense	(14,000,000)		(13,000,000)								(14,000,000)	(13,000,000)
Other			900,000						900,000
Goodwill, Ending Balance	807,850,000		613,369,000				807,900,000		613,400,000
Intangible assets, non-amortizing, Ending Balance	881,100,000		655,300,000		73,200,000	41,900,000
Other intangible assets, amortizing, Ending Balance	44,700,000	[1]	36,300,000	[1]							44,700,000	36,300,000
Goodwill and other intangible assets, Ending Balance	$ 925,800,000		$ 691,600,000

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

[2] Represents contingent consideration for acquisitions prior to December 15, 2008.