Share-Based Compensation (Narrative) (Details)		3 Months Ended
	May 16, 2019 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) qtr stock-based_complensation_plan $ / shares shares	Mar. 31, 2019 USD ($)	Dec. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans | stock-based_complensation_plan		3
Common stock reserved for issuance pursuant to outstanding awards | shares		510,450		520,513
Weighted average grant date fair value (in dollars per share) | $ / shares		$ 0
Number of shares vested | shares		2,000
Aggregate fair value of outstanding restricted shares and restricted stock units		$ 1,100,000
Aggregate fair value of restricted shares and restricted stock units		45,000	$ 43,000
Proceeds from exercise of stock options		$ 85,000	59,000
Shares, Granted (in shares) | shares		0
Unvested shares | shares		66,204		68,204
Equity based compensation expense		$ 272,000	244,000
Unrecognized compensation cost related to non-vested equity based compensation		$ 2,100,000
Unrecognized equity based compensation weighted average period, years		2 years 9 months 14 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares) | shares		185,351
Common stock reserved for issuance pursuant to outstanding awards | shares		558,654
Vesting period, years		4 years
Expiration of stock options from date of grant		7 years
Weighted average remaining contractual term, years		3 years 4 months 24 days
Aggregate intrinsic value for all options outstanding		$ 2,900,000
Weighted average remaining contractual term for exercisable options, years		2 years 6 months
Aggregate intrinsic value of exercisable options		$ 2,800,000
Aggregate intrinsic value of stock options exercised		140,000	57,000
Proceeds from exercise of stock options		85,000	59,000
Equity based compensation expense		$ 114,000	107,000
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		$ 101,000	76,000
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
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		$ 23,000	29,000
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
Common stock reserved for issuance pursuant to outstanding awards | shares		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
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		$ 34,000
Number of shares vested | shares		6,000
Equity based compensation expense		$ 34,000	$ 32,000