Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Total assets measured at fair value	$ 15,117	$ 16,032
Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	1,708	1,726
Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	11,901	13,289
Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	1,508	1,017
Level 1 [Member]
ASSETS
Total assets measured at fair value	1,708	1,726
Level 1 [Member] | Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	1,708	1,726
Level 2 [Member]
ASSETS
Total assets measured at fair value	13,409	14,306
Level 2 [Member] | Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	11,901	13,289
Level 2 [Member] | Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	$ 1,508	$ 1,017