Liquidity (Details Textual) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	[1]	Jun. 30, 2014	Dec. 31, 2013
Liquidity Details [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 150,221	$ 158,883		$ 1,762	$ 2,101
Line of Credit Facility, Remaining Borrowing Capacity	6,800
Line of Credit Facility, Maximum Borrowing Capacity	10,000
Additional Aggregate Consideration For Purchased Assets	$ 6,000

[1] Derived from the audited December 31, 2014 financial statements