Common Stock And Stock Options (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock for which awards can be granted	251,000
Shares issued in lieu of cash for director fees under director program	0	0	0
Maximum amount of common stock participants may elect to purchase	$ 100
Window period	20 days
Shares repurchased under management purchase program	0	0	0
Weighted average remaining contractual life of options exercisable, years	4 years 4 months 13 days	5 years 7 months 2 days
Total intrinsic value of options exercised	$ 631	$ 76	$ 630
Weighted average fair value of options granted	$ 4.20	$ 4.17	$ 4.50
Forfeiture rate	0.00%
Stock option expense	$ 844	$ 685	$ 579
Stock options exercised using cashless method	189,000
Unrecognized compensation costs related to non-vested awards	$ 995
Unrecognized compensation costs related to non-vested awards, recognition period	1 year 9 months 22 days
Shares issued from Equity Offering		$ 3,678
Shares issued from Equity Offering, shares		805,000
2015 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock for which awards can be granted	500,000
2001 Stock Option Plan And Non-Employee Directors' Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock for which awards can be granted	925,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares approved under purchase plan	300,000
Shares purchased for award	11,000	18,000	14,000
Minimum [Member] | 2015 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options under equity incentive plan	3 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options under equity incentive plan	3 years
Maximum [Member] | 2015 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options under equity incentive plan	10 years