Investments (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Investments at fair value	$ 81,564,000	$ 0
Gross unrealized losses on certain investments	28,000
Amount of investments held other-than-temporarily impaired	0
Proceeds from sales and maturities of investments	2,200,000
Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Proceeds from sales and maturities of investments	$ 1,200,000