Supplemental Balance Sheet, Income Statement and Cash Flow Information (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investment income (loss)
Interest and dividend income	$ 1,068	$ 2,028	$ 1,602	$ 2,998
Gains (losses) on investments, net	113	5,038	548	5,048
Investment income (loss)	$ 1,181	$ 7,066	$ 2,150	8,046
Realized gains from the sale of available-for-sale securities				$ 5,000