Acquisitions and Dispositions (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Goodwill	$ 390,081	$ 656,364	$ 641,669
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Fixed assets, net	21	509
Identifiable intangible assets	3,062	9,205
Goodwill	2,871	14,695
Other assets	128	66
Total assets acquired	6,082	24,475
Accounts payable and accrued liabilities	1,444	1,955
Total liabilities assumed	1,444	1,955
Net assets acquired	$ 4,638	$ 22,520