Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Provision for doubtful accounts	$ 200		$ 436	$ 106
Allowance for doubtful accounts	$ 900		$ 900		$ 1,000
Stock Options [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of potential diluted securities outstanding	579,000	695,000	579,000	695,000
Number of securities included in calculation of diluted earnings per share	296,000	327,000	304,000	316,000
Restricted Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of potential diluted securities outstanding	72,000	154,000	72,000	154,000
Number of securities included in calculation of diluted earnings per share	37,000	62,000	63,000	78,000