Financial Instruments (Fair Value Of Investments) (Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Amortized cost	$ 110,431	$ 83,266
Gross unrealized holding gains	17	13
Gross unrealized holding losses	(114)	(35)
Fair value	110,334	83,244
Corporate
Amortized cost	72,083	50,822
Gross unrealized holding gains	1	3
Gross unrealized holding losses	(110)	(31)
Fair value	71,974	50,794
Government agency
Amortized cost	38,348	32,444
Gross unrealized holding gains	16	10
Gross unrealized holding losses	(4)	(4)
Fair value	$ 38,360	$ 32,450