Changes in Carrying Amount of Goodwill (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
Goodwill [Roll Forward]
Beginning balance	$ 1,690,284
Business acquisitions and adjustments to previously recorded goodwill	227,261	197,600
Exchange rate effects	3,371
Ending balance	1,920,916	1,690,284
North America
Goodwill [Roll Forward]
Beginning balance	1,339,831
Business acquisitions and adjustments to previously recorded goodwill	17,623
Exchange rate effects	(4,407)
Ending balance	1,353,047
Europe
Goodwill [Roll Forward]
Beginning balance	350,453
Business acquisitions and adjustments to previously recorded goodwill	209,638
Exchange rate effects	7,778
Ending balance	$ 567,869

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details