Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Loss	$ 50	$ 73
Available-For-Sale Securities Number of Securities Owned	47
Available-For-Sale Securities Number Of Securities Owned Unrealized Losses	35
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Loss	$ 100
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities, Total		1,800
Available-for-sale Securities, Gross Realized Gain (Loss)		$ 600