Marketable Securities (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) Number	Dec. 31, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Securities Number of Securities Owned | Number	42
Available-For-Sale Securities Number Of Securities Owned Unrealized Losses | Number	14
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | $	$ 18	$ 50
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | $	$ 100