Short-Term Investments (Unrealized Gains And Losses Related To Cash, Cash Equivalents, And Short-Term Investments Designated As Available-For-Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 106,817	$ 74,746
Gross Unrealized Gain	78	89
Gross Unrealized Loss	(145)	(182)
Cumulative Translation Adjustment	(1,466)	(1,536)
Fair Value	105,284	73,117
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	92,561	72,986
Gross Unrealized Gain	78	89
Gross Unrealized Loss	(145)	(182)
Cumulative Translation Adjustment	(1,466)	(1,536)
Fair Value	91,028	71,357
U.S. Treasuries And Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	12,496
Fair Value	12,496
Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	1,760	1,760
Fair Value	$ 1,760	$ 1,760