Adoption Of Accounting Standards Update No. 2016-09, Improvements To Employee Share Based Payment Accounting (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 19,108,000	$ 18,037,000
Common stock	34,052,000	32,801,000
Deferred tax assets	5,484,000	$ 5,323,000
Excess tax benefit from the exercise of stock options	207,000
ASU No. 2016-09 [Member] | Restatement Adjustment [Member] | Recognition of the deferred tax assets for previously unrecognized excess tax benefits [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	278,000
ASU No. 2016-09 [Member] | Restatement Adjustment [Member] | Change in accounting for stock option forfeitures [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	(16,000)
Common stock	23,000
Deferred tax assets	$ 7,000