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	Dec. 31, 2011	Dec. 31, 2010
Goodwill [Roll Forward]
Beginning balance	$ 1,690,284	$ 1,476,063	$ 1,032,973	$ 938,783
Business acquisitions and adjustments to previously recorded goodwill	227,261	197,602	442,208	91,757
Exchange rate effects	3,371	16,619	882	2,433
Ending balance	1,920,916	1,690,284	1,476,063	1,032,973
North America
Goodwill [Roll Forward]
Beginning balance	1,339,831	1,136,630	1,032,973	938,783
Business acquisitions and adjustments to previously recorded goodwill	17,623	201,742	105,177	91,757
Exchange rate effects	(4,407)	1,459	(1,520)	2,433
Ending balance	1,353,047	1,339,831	1,136,630	1,032,973
Europe
Goodwill [Roll Forward]
Beginning balance	350,453	339,433	0
Business acquisitions and adjustments to previously recorded goodwill	209,638	(4,140)	337,031
Exchange rate effects	7,778	15,160	2,402
Ending balance	$ 567,869	$ 350,453	$ 339,433

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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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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-Name Statement of Financial Accounting Standard (FAS)

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