Share-Based Compensation (Narrative) (Details)		3 Months Ended		9 Months Ended
	May 16, 2019 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) qtr stock-based_complensation_plan shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) qtr stock-based_complensation_plan $ / shares shares	Sep. 30, 2018 USD ($)	Dec. 31, 2018 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		488,892		488,892		523,042
Weighted average grant date fair value (in dollars per share) | $ / shares				$ 17.26
Number of shares vested | shares				6,000
Aggregate fair value of outstanding restricted shares and restricted stock units | $		$ 822,000		$ 822,000
Aggregate fair value of restricted shares and restricted stock units | $				105,000
Proceeds from exercise of stock options | $				$ 173,000	$ 452,000
Shares, Granted (in shares) | shares				8,000
Unvested shares | shares		57,536		57,536		56,411
Equity based compensation expense | $		$ 244,000	$ 217,000	$ 737,000	701,000
Unrecognized compensation cost related to non-vested equity based compensation | $		$ 1,600,000		$ 1,600,000
Unrecognized equity based compensation weighted average period, years				2 years 4 months 6 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares) | shares		273,764		273,764
Common stock reserved for issuance pursuant to outstanding awards | shares		524,428		524,428
Vesting period, years				4 years
Expiration of stock options from date of grant				7 years
Weighted average remaining contractual term, years				3 years 3 months 18 days
Aggregate intrinsic value for all options outstanding | $		$ 2,100,000		$ 2,100,000
Weighted average remaining contractual term for exercisable options, years				2 years 7 months 6 days
Aggregate intrinsic value of exercisable options | $		1,900,000		$ 1,900,000
Aggregate intrinsic value of stock options exercised | $				121,000
Proceeds from exercise of stock options | $				173,000	452,000
Fair value of shares vested | $				5,000
Equity based compensation expense | $		110,000	94,000	$ 327,000	328,000
Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Granted (in shares) | shares				8,000
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
Shares, Granted (in shares) | shares				0
Equity based compensation expense | $		$ 78,000	59,000	$ 231,000	176,000
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		156,688		156,688
Stock issued during period, shares | shares				17,781
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 | $		$ 21,000	31,000	$ 81,000	86,000
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]
Number of shares available for future issuance (in shares) | shares		52,000		52,000
Common stock reserved for issuance pursuant to outstanding awards | shares		16,000		16,000
Number of shares granted for non-employee directors upon re-election, shares | shares				2,000
Number of quarterly installments in which awards will vest | qtr		4		4
Stock issued during period, shares | shares	8,000
Stock granted, value | $	$ 138,000
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 17.26
Aggregate intrinsic value for all options outstanding | $		$ 86,000		$ 86,000
Number of shares vested | shares				2,000
Unvested shares | shares		6,000		6,000
Equity based compensation expense | $		$ 35,000	$ 33,000	$ 98,000	$ 111,000