Other Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross	$ 332,618,000		$ 323,281,000
Less accumulated amortization	(162,512,000)		(151,697,000)
Other intangible assets, net	170,106,000		171,584,000
Amortization expense for finite-lived intangible assets	8,500,000	6,700,000
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross	292,209,000		286,164,000
Less accumulated amortization	(147,673,000)		(137,782,000)
Other intangible assets, net	144,536,000		148,382,000
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross	9,159,000		9,264,000
Less accumulated amortization	(5,669,000)		(5,438,000)
Other intangible assets, net	3,490,000		3,826,000
Trade Names and Licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross	31,250,000		27,853,000
Less accumulated amortization	(9,170,000)		(8,477,000)
Other intangible assets, net	$ 22,080,000		$ 19,376,000