Basis of presentation and summary of significant accounting policies Other Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other Income and Expenses [Abstract]
Professional Fees	$ 81	$ 257	$ 334	$ 811
Interest income included in other income	574	379	1,428	864
Gain (Loss) on Investments	9,676	2,121	13,785	5,833
Other income	$ 10,331	$ 2,757	$ 15,547	$ 7,508