Significant Accounting Policies (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended			9 Months Ended	0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Common Class A	Mar. 28, 2012 Doner	Sep. 30, 2014 Doner	Dec. 31, 2013 Doner
Significant Accounting Policies [Line Items]
Cost Method Investments	$ 15,048		$ 15,048		$ 12,452
Proceeds from Sale of Other Investments			7,700
Consolidated Accounts Receivable Percentage			10.00%
Consolidated Largest Client Revenue			10.00%
Restricted Cash and Cash Equivalents, Noncurrent	6,464		6,464		44
Business Acquisition, Increase (Decrease) in Contingent Purchase Price Obligation	2,623	717	14,716	5,400
Business Combination, Acquisition Related Costs	1,658	427	3,713	1,438
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage							30.00%
Ownership Interest Percentage Increase On Exercise Of Option							70.00%
Assets	1,707,328	1,365,687	1,707,328	1,365,687	1,425,227			231,216	224,964
Liabilities	1,794,047		1,794,047		1,553,305			173,768	179,500
Aggregate Grant Date Fair Value			$ 7,483
Stock Issued During Period, Shares, Restricted Stock Award, Gross			319,283			795,883