Accounting For Stock-Based Compensation (Narrative) (Details)			3 Months Ended		6 Months Ended
	May 11, 2017 USD ($) $ / shares shares	May 20, 2016 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) stock-based_complensation_plan shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) stock-based_complensation_plan $ / shares shares	Jun. 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			506,875		506,875		547,625
Weighted average grant date fair value (in dollars per share) | $ / shares					$ 0
Tax benefit realized from exercise of stock options					$ 208,000
Fair value of shares vested					$ 117,000
Shares, Granted (in shares) | shares					0
Equity based compensation expense			$ 212,000	$ 409,000	$ 400,000	$ 552,000
Unrecognized compensation cost related to non-vested equity based compensation			$ 1,400,000		$ 1,400,000
Unrecognized equity based compensation weighted average period, years					1 year 6 months 4 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future awards | shares			427,739		427,739
Common stock reserved for issuance pursuant to outstanding awards | shares			531,424		531,424
Vesting period, years					4 years
Expiration of stock options from date of grant					7 years
Weighted average remaining contractual term, years					4 years 4 months 24 days
Aggregate intrinsic value for all options outstanding			$ 5,900,000		$ 5,900,000
Weighted average remaining contractual term for exercisable options, years					3 years 10 months 24 days
Aggregate intrinsic value of exercisable options			3,000,000		$ 3,000,000
Aggregate intrinsic value of stock options exercised					668,000
Proceeds from exercise of stock options					321,000	258,000
Equity based compensation expense			115,000	226,000	$ 229,000	321,000
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			837,000		$ 837,000
Fair value of shares vested					$ 170,000
Shares, Granted (in shares) | shares					0
Equity based compensation expense			$ 48,000	31,000	$ 96,000	$ 63,000
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			59,276		59,276
Shares, Granted (in shares) | shares					0	0
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			$ 26,000	16,000	$ 52,000	$ 32,000
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	$ 165,000	$ 139,000
Grant date fair value (in dollars per share) | $ / shares		$ 8.71
Equity based compensation expense			$ 23,000	$ 136,000	$ 23,000	$ 136,000