Financial Instruments, Gains (Losses) on Derivatives, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financial Instruments [Abstract]
Purchase of publicly traded equity securities	$ 869		$ 869	$ 0
Trading securities	900		900
Gains (Losses) on Derivatives, Net [Abstract]
Gains (losses) on derivatives, net	$ (100)	$ 100	$ (200)	$ (100)