Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
ASSETS
Total assets measured at fair value	$ 18,546	$ 16,032
Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	1,937	1,726
Cash And Cash Equivalents [Member] | Corporate Bonds [Member]
ASSETS
Total cash and cash equivalents	500
Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	14,590	13,289
Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	1,519	1,017
Level 1 [Member]
ASSETS
Total assets measured at fair value	1,937	1,726
Level 1 [Member] | Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	1,937	1,726
Level 2 [Member]
ASSETS
Total assets measured at fair value	16,609	14,306
Level 2 [Member] | Cash And Cash Equivalents [Member] | Corporate Bonds [Member]
ASSETS
Total cash and cash equivalents	500
Level 2 [Member] | Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	14,590	13,289
Level 2 [Member] | Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	$ 1,519	$ 1,017