Accounting For Stock-Based Compensation (Narrative) (Details)			3 Months Ended		9 Months Ended
	May 11, 2017 USD ($) $ / shares shares	May 20, 2016 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) stock-based_complensation_plan shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) stock-based_complensation_plan $ / shares shares	Sep. 30, 2016 USD ($) shares	Dec. 31, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans | stock-based_complensation_plan			3		3
Common stock reserved for issuance pursuant to outstanding awards | shares			505,625		505,625		547,625
Weighted average grant date fair value (in dollars per share) | $ / shares					$ 0
Excess tax benefit from the exercise of stock options					$ 207,000
Proceeds from exercise of stock options					330,000	$ 425,000
Fair value of shares vested					$ 130,000
Shares, Granted (in shares) | shares					0
Equity based compensation expense			$ 240,000	$ 142,000	$ 640,000	694,000
Unrecognized compensation cost related to non-vested equity based compensation			$ 1,300,000		$ 1,300,000
Unrecognized equity based compensation weighted average period, years					1 year 3 months
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future awards | shares			429,939		429,939
Common stock reserved for issuance pursuant to outstanding awards | shares			530,174		530,174
Vesting period, years					4 years
Expiration of stock options from date of grant					7 years
Weighted average remaining contractual term, years					4 years 2 months 12 days
Aggregate intrinsic value for all options outstanding			$ 3,800,000		$ 3,800,000
Weighted average remaining contractual term for exercisable options, years					3 years 8 months 12 days
Aggregate intrinsic value of exercisable options			2,000,000.0		$ 2,000,000.0
Aggregate intrinsic value of stock options exercised					679,000
Proceeds from exercise of stock options					330,000	425,000
Equity based compensation expense			116,000	88,000	$ 345,000	409,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, years					4 years
Restricted stock units to common stock ratio, shares entitled, shares | shares					1
Aggregate intrinsic value for all options outstanding			659,000		$ 659,000
Fair value of shares vested					$ 170,000
Shares, Granted (in shares) | shares					0
Equity based compensation expense			$ 49,000	32,000	$ 145,000	$ 95,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares) | shares			40,872		40,872
Shares, Granted (in shares) | shares					18,404	36,481
Maximum contribution per plan year					$ 6,500
Employees can purchase stock at the percentage rate of the lower of the market price on the first or last day of the offering period (as a percent)					85.00%
Equity based compensation expense			$ 33,000	$ 22,000	$ 85,000	$ 54,000
Employee Stock Purchase Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payroll deduction for employee stock purchase plan percentage					1.00%
Employee Stock Purchase Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payroll deduction for employee stock purchase plan percentage					10.00%
Non-Employee Director Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance pursuant to outstanding awards | shares			16,000		16,000
Number of shares available for future issuance (in shares) | shares			68,000		68,000
Number of shares granted for non-employee directors upon re-election, shares | shares					2,000
Options granted to non-employee directors upon re-election | shares		16,000
Stock issued during period, shares | shares	8,000	8,000
Stock granted, value	$ 167,000	$ 136,000
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 20.90	$ 16.97
Options granted in period, fair value		$ 139,000			$ 98,000
Grant date fair value (in dollars per share) | $ / shares		$ 8.71
Number of shares vested | shares					2,000
Fair value of shares vested					$ 31,000
Equity based compensation expense			$ 42,000		$ 65,000	$ 136,000