Significant Accounting Policies (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended	0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Common Class A	Mar. 28, 2012 Doner	Jun. 30, 2014 Doner	Dec. 31, 2013 Doner
Significant Accounting Policies [Line Items]
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	6,817		6,817		44
Business Acquisition, Increase (Decrease) in Contingent Purchase Price Obligation	4,071	2,387	12,093	4,683
Business Combination, Acquisition Related Costs	984	475	2,055	1,011
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage							30.00%
Ownership Interest Percentage Increase On Exercise Of Option							70.00%
Assets	1,685,018	1,389,443	1,685,018	1,389,443	1,425,227			209,839	224,964
Liabilities	1,772,529		1,772,529		1,553,305			150,653	179,501
Aggregate Grant Date Fair Value			$ 5,237
Stock Issued During Period, Shares, Restricted Stock Award, Gross			213,783			802,883