Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Provision for doubtful accounts	$ 200		$ 681	$ 168
Allowance for doubtful accounts	$ 800		$ 800		$ 1,000
Accounting Standards Update 2016-13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, immaterial effect	true		true
Accounting Standards Update 2017-04 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, immaterial effect	true		true
Accounting Standards Update 2018-15 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, immaterial effect	true		true
Stock Options [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of potential diluted securities outstanding	523,000	650,000	523,000	650,000
Number of securities included in calculation of diluted earnings per share	301,000	359,000	303,000	335,000
Restricted Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of potential diluted securities outstanding	149,000	147,000	149,000	147,000
Number of securities included in calculation of diluted earnings per share	38,000	78,000	58,000	81,000