Financial Instruments (Fair Value Of Investments) (Details 1) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Amortized cost	$ 131,342	$ 83,266
Gross unrealized holding gains	41	13
Gross unrealized holding losses	(49)	(35)
Fair value	131,334	83,244
Corporate
Amortized cost	94,058	50,822
Gross unrealized holding gains	19	3
Gross unrealized holding losses	(45)	(31)
Fair value	94,032	50,794
Government agency
Amortized cost	37,284	32,444
Gross unrealized holding gains	22	10
Gross unrealized holding losses	(4)	(4)
Fair value	$ 37,302	$ 32,450