Fair Value Measurements (Fair Value, Investment Securities Measured on Recurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair value of securities at beginning of period	$ 15
Unrealized loss on fair value of securities	1	$ 8
Fair value of securities at end of period	14
Level 1 Estimated Fair Value [Member]
Fair value of securities at beginning of period	15	112
Unrealized loss on fair value of securities	(1)	(8)
Fair value of securities at end of period	$ 14	$ 104