Goodwill And Other Intangible Assets (Goodwill And Intangible Assets) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 years		Dec. 31, 2010 years		Dec. 31, 2009
Goodwill And Other Intangible Assets [Line Items]
Gross carrying amount	$ 97,600,000	[1]	$ 75,200,000	[1]
Less: accumulated amortization	(52,900,000)	[1]	(38,900,000)	[1]
Amortizing intangible assets, net	44,700,000	[1]	36,300,000	[1]
Goodwill	807,850,000		613,369,000
Non-amortizing intangible assets	881,100,000		655,300,000
Goodwill and other intangible assets	925,800,000		691,600,000		595,400,000
Weighted average amortization period, in years	14	[1]	14	[1]
Trade Names [Member]
Goodwill And Other Intangible Assets [Line Items]
Non-amortizing intangible assets	35,300,000		35,300,000
Pre-Qualifications [Member]
Goodwill And Other Intangible Assets [Line Items]
Non-amortizing intangible assets	31,300,000
Other Intangible Assets [Member]
Goodwill And Other Intangible Assets [Line Items]
Non-amortizing intangible assets	$ 6,600,000		$ 6,600,000

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