STOCKHOLDERS' EQUITY, STOCK PLANS AND STOCK-BASED COMPENSATION EXPENSE (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	52,938		37,925
Employee Stock Purchase Plan [Abstract]
ESPP offering and purchase period	6 months
Weighted Average Exercise Price [Roll Forward]
Closing price of company stock (in dollars per share)	$ 9.00		$ 7.45		$ 8.29
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number of Exercisable Options (in shares)			1,806,558
Weighted Average Exercise Price (in dollars per share)			$ 10.86
Performance Stock Units [Abstract]
Threshold percentage of revenue for performance goal (in hundredths)	50.00%
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	$ 3,160,000		$ 3,907,000		$ 4,650,000
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	1,667,000		1,360,000		518,000
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	6,000		22,000		8,000
Stock-based compensation expense by department
Stock-based compensation expense	3,160,000		3,907,000		4,650,000
Valuation Assumptions and Fair Value of Stock Option and ESPP Grants [Abstract]
Number of shares withheld for employees tax obligations (in shares)	14,974		16,629		14,283
Amount withheld for employees' tax obligations	101,000		146,000		126,000
Cost of revenue [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	658,000		659,000		724,000
Stock-based compensation expense by department
Stock-based compensation expense	658,000		659,000		724,000
Sales and marketing [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	657,000		788,000		1,189,000
Stock-based compensation expense by department
Stock-based compensation expense	657,000		788,000		1,189,000
Research and development [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	514,000		698,000		629,000
Stock-based compensation expense by department
Stock-based compensation expense	514,000		698,000		629,000
General and administrative [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	1,331,000		1,762,000		2,108,000
Stock-based compensation expense by department
Stock-based compensation expense	1,331,000		1,762,000		2,108,000
$ 4.25-$ 6.54 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 4.25
Range of Exercise Prices, upper limit (in dollars per share)	$ 6.54
Option Outstanding, Number of Outstanding (in shares)	81,180
Option Outstanding, Weighted Average Remaining Contractual Life	1 year 6 months 4 days
Number of Exercisable Options (in shares)	79,283
Weighted Average Exercise Price (in dollars per share)	$ 5.14
$ 6.88-$ 6.88 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 6.88
Range of Exercise Prices, upper limit (in dollars per share)	$ 6.88
Option Outstanding, Number of Outstanding (in shares)	765,500
Option Outstanding, Weighted Average Remaining Contractual Life	6 years 6 months 22 days
Number of Exercisable Options (in shares)	0
Weighted Average Exercise Price (in dollars per share)	$ 0
$ 8.66-$8.66 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 8.66
Range of Exercise Prices, upper limit (in dollars per share)	$ 8.66
Option Outstanding, Number of Outstanding (in shares)	518,596
Option Outstanding, Weighted Average Remaining Contractual Life	3 years 4 months 28 days
Number of Exercisable Options (in shares)	475,115
Weighted Average Exercise Price (in dollars per share)	$ 8.66
$ 8.72-$8.72 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 8.72
Range of Exercise Prices, upper limit (in dollars per share)	$ 8.72
Option Outstanding, Number of Outstanding (in shares)	694,758
Option Outstanding, Weighted Average Remaining Contractual Life	5 years 4 months 17 days
Number of Exercisable Options (in shares)	286,635
Weighted Average Exercise Price (in dollars per share)	$ 8.72
$ 7.11-$ 8.49 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 7.11
Range of Exercise Prices, upper limit (in dollars per share)	$ 8.49
Option Outstanding, Number of Outstanding (in shares)	427,626
Option Outstanding, Weighted Average Remaining Contractual Life	3 years 6 months 22 days
Number of Exercisable Options (in shares)	317,441
Weighted Average Exercise Price (in dollars per share)	$ 8.37
$ 10.24-$10.24 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 10.24
Range of Exercise Prices, upper limit (in dollars per share)	$ 10.24
Option Outstanding, Number of Outstanding (in shares)	557,917
Option Outstanding, Weighted Average Remaining Contractual Life	4 years 4 months 6 days
Number of Exercisable Options (in shares)	386,253
Weighted Average Exercise Price (in dollars per share)	$ 10.24
$ 10.43-$14.14 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 10.43
Range of Exercise Prices, upper limit (in dollars per share)	$ 14.14
Option Outstanding, Number of Outstanding (in shares)	411,033
Option Outstanding, Weighted Average Remaining Contractual Life	1 year 11 months 19 days
Number of Exercisable Options (in shares)	411,033
Weighted Average Exercise Price (in dollars per share)	$ 11.81
$ 8.52-$ 8.52 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 8.52
Range of Exercise Prices, upper limit (in dollars per share)	$ 8.52
Option Outstanding, Number of Outstanding (in shares)	18,000
Option Outstanding, Weighted Average Remaining Contractual Life	6 years 18 days
Number of Exercisable Options (in shares)	2,708
Weighted Average Exercise Price (in dollars per share)	$ 8.52
$ 8.75-$9.74 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 8.75
Range of Exercise Prices, upper limit (in dollars per share)	$ 9.74
Option Outstanding, Number of Outstanding (in shares)	102,000
Option Outstanding, Weighted Average Remaining Contractual Life	5 years 2 months 9 days
Number of Exercisable Options (in shares)	54,563
Weighted Average Exercise Price (in dollars per share)	$ 9.28
$ 14.78-$25.73 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 14.78
Range of Exercise Prices, upper limit (in dollars per share)	$ 25.73
Option Outstanding, Number of Outstanding (in shares)	211,629
Option Outstanding, Weighted Average Remaining Contractual Life	1 year 10 months 6 days
Number of Exercisable Options (in shares)	211,629
Weighted Average Exercise Price (in dollars per share)	$ 20.47
$ 4.25-$25.73 [Member]
Share-based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit (in dollars per share)	$ 4.25
Range of Exercise Prices, upper limit (in dollars per share)	$ 25.73
Option Outstanding, Number of Outstanding (in shares)	3,788,239
Option Outstanding, Weighted Average Remaining Contractual Life	4 years 4 months 2 days
Number of Exercisable Options (in shares)	2,224,660
Weighted Average Exercise Price (in dollars per share)	$ 10.50
Stock Options [Member]
Shares Available for Grant [Roll Forward]
Beginning Balance (in shares)	474,537		1,005,447		1,840,381
Additional shares reserved (in shares)	1,910,000	[1]
Options granted (in shares)	(921,500)	[2]	(1,206,500)	[2]	(961,500)	[2]
Options cancelled (expired or forfeited) (in shares)	470,732	[2]	746,273	[2]	267,274	[2]
Stock awards granted (in shares)	(314,159)		(77,225)		(146,291)
Restricted stock units cancelled (expired or forfeited) (in shares)	24,746		6,542		5,583
Ending Balance (in shares)	1,644,356		474,537		1,005,447		1,840,381
Options Outstanding [Roll Forward]
Beginning Balance (in shares)	3,549,022		3,296,419		2,692,555
Options granted (in shares)	921,500	[2]	1,206,500	[2]	961,500	[2]
Options exercised (in shares)	(211,551)		(207,624)		(90,362)
Options cancelled (expired or forfeited) (in shares)	(470,732)	[2]	(746,273)	[2]	(267,274)	[2]
Ending Balance (in shares)	3,788,239		3,549,022		3,296,419		2,692,555
Number of shares exercisable (in shares)	2,224,660
Weighted Average Exercise Price [Roll Forward]
Beginning Balance (in dollars per share)	$ 9.92		$ 10.93		$ 10.87
Options granted (in dollars per share)	$ 7.04	[2]	$ 8.61	[2]	$ 10.14	[2]
Options exercised (in dollars per share)	$ 7.00		$ 5.92		$ 3.74
Options cancelled (expired or forfeited) (in dollars per share)	$ 9.45	[2]	$ 13.40	[2]	$ 9.91	[2]
Ending Balance (in dollars per share)	$ 9.44		$ 9.92		$ 10.93		$ 10.87
Weighted-Average Exercisable (in dollars per share)	$ 10.50
Weighted-Average Remaining Contractual life	4 years 3 months 18 days		4 years 7 months 6 days		4 years 4 months 24 days		5 years 1 month 6 days
Weighted-Average Remaining Contractual life exercisable	3 years 3 months 18 days
Aggregate Intrinsic Value	2,600,000	[3]	400,000	[3]	1,100,000	[3]	1,600,000	[3]
Aggregate Intrinsic Value	800,000	[3]
Total intrinsic value	397,000		521,000		128,000
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	2,421,000		3,047,000		3,628,000
Stock-based compensation expense by department
Stock-based compensation expense	2,421,000		3,047,000		3,628,000
Unrecognized compensation cost	4,000,000
Weighted-average amortization period	2 years 5 months 16 days
Valuation Assumptions and Fair Value of Stock Option and ESPP Grants [Abstract]
Estimated fair value of grants during the year	$ 2.47		$ 3.10		$ 3.76
Expected term	4 years 2 months 1 day	[4]	4 years 1 month 24 days	[4]	3 years 10 months 2 days	[4]
Risk-free interest rate (in hundredths)	0.45%	[5]	1.41%	[5]	1.73%	[5]
Volatility (in hundredths)	44.00%	[6]	43.00%	[6]	46.00%	[6]
Dividend yield (in hundredths)	0.00%	[7]	0.00%	[7]	0.00%	[7]
Restricted stock units [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional restricted stock issued	148,188		77,225
Number of Shares [Roll Forward]
Beginning Balance (in shares)	55,253		67,096
Granted (in shares)	148,188		77,225
Vested (in shares)	(41,522)	[8]	(85,526)
Forfeited (in shares)	(13,210)		(6,542)
Ending Balance (in shares)	148,709		55,253		67,096
Weighted Average Grant Date Fair Value [Roll Forward]
Beginning Balance (in dollars per share)	$ 9.55		$ 10.24
Granted (in dollars per share)	$ 6.85		$ 8.32
Vested (in dollars per share)	$ 9.79	[8]	$ 8.93
Forfeited (in dollars per share)	$ 7.39		$ 9.99
Ending Balance (in dollars per share)	$ 6.99		$ 9.55		$ 10.24
Aggregate Fair Value	279,000	[10],[8],[9]	691,000
Fair value vested awards	407,000
Performance Stock Units [Abstract]
Performance stock units granted (in shares)	148,188		77,225
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	501,000		775,000		927,000
Stock-based compensation expense by department
Stock-based compensation expense	501,000		775,000		927,000
ESPP [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	100,000		85,000		95,000
Stock-based compensation expense by department
Stock-based compensation expense	100,000		85,000		95,000
Unrecognized compensation cost	43,000
Weighted-average amortization period	3 months 29 days
Stock Purchase Plan [Member]
Stock-based Compensation [Abstract]
Allocated Share-based Compensation Expense	138,000
Stock-based compensation expense by department
Stock-based compensation expense	138,000
Valuation Assumptions and Fair Value of Stock Option and ESPP Grants [Abstract]
Estimated fair value of grants during the year	$ 2.16		$ 2.06		$ 2.41
Expected term	6 months	[4]	6 months	[4]	6 months	[4]
Risk-free interest rate (in hundredths)	0.15%	[5]	0.08%	[5]	0.20%	[5]
Volatility (in hundredths)	43.00%	[6]	39.00%	[6]	40.00%	[6]
Dividend yield (in hundredths)	0.00%	[7]	0.00%	[7]	0.00%	[7]
Performance Shares [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional restricted stock issued	42,250
Number of Shares [Roll Forward]
Granted (in shares)	42,250
Performance Stock Units [Abstract]
Performance stock units granted (in shares)	42,250
Performance stock units or PSUs vesting date	Jun. 01, 2013
Number of performance goals	3
Common stock issuable if revenue achievement is below 50% (in hundredths)	0.00%
Common stock issuable if revenue achievement is above 50% (in hundredths)	200.00%
2004 Equity Incentive Plan [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued (in shares)	0		37,925
Share based compensation by share based payment fully vested stock awards grant date fair value	$ 60,000
Employee Stock Purchase Plan [Abstract]
Shares of common stock reserved for issuance for employee purchase plan (in shares)	1,750,000
2004 Equity Incentive Plan [Member] | Stock Options [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Terms of award	Options granted under the 1998 Plan and 2004 Equity Incentive Plan may be incentive stock options or non-statutory stock options. Stock purchase rights may also be granted under the 2004 Equity Incentive Plan. Incentive stock options may only be granted to employees. The Board of Directors determines the period over which options become exercisable. Options granted under the Plan to employees generally vest over a four year term from the vesting commencement date and become exercisable 25% on the first anniversary of the vesting commencement date and an additional 1/48th on the last day of each calendar month until all of the shares have become exercisable. During 2012, 2011 and 2010 the officers of the Company were granted options that vest over a three year term at the rate of 1/3rd on the one year anniversary of the vesting commencement date and 1/36th thereafter.The contractual term of the options granted in 2012, 2011 and 2010 was seven years.
2004 Equity Incentive Plan [Member] | Restricted stock units [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Terms of award	In accordance with the 2004 Equity Incentive Plan, prior to 2012, the Company's non-employee directors are granted $60,000 of grant date fair value, fully vested, stock awards annually on the date of the Company's Annual Meeting of stockholders. Commencing with 2012, the Company's non-employee directors get $60,000 of restricted stock units annually that cliff vest on the one year anniversary of the grant date. In addition, in the year ended December 31, 2012 and 2011, the Company's Board of Directors granted 95,250 and 39,300, respectively, of RSUs to certain members of the Company's management. These RSUs vest at the rate of one-third on June 1of the year of grant, and one-third in each of the subsequent two years. The Company measured the fair market values of the underlying stock on the dates of grant and recognizes the stock-based compensation expense using the straight-line method over the vesting period.
Additional restricted stock issued	95,250		39,300
Number of Shares [Roll Forward]
Granted (in shares)	95,250		39,300
Performance Stock Units [Abstract]
Performance stock units granted (in shares)	95,250		39,300
2004 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued (in shares)	46,982		45,161
Common stock capital shares reserved for future issuance (in shares)	1,009,954
Employee Stock Purchase Plan [Abstract]
Shares of common stock	600,000
Percentage of outstanding shares of common stock (in hundredths)	2.00%
Purchase price of common stock (in hundredths)	85.00%
1998 Stock Plan [Member]
Employee Stock Purchase Plan [Abstract]
Shares of common stock reserved for issuance for employee purchase plan (in shares)	4,650,000
1998 Stock Plan [Member] | Stock Options [Member]
Share-based Compensation Arrangement By Share Based Payment Award [Line Items]
Terms of award	Options granted under the 1998 Plan and 2004 Equity Incentive Plan may be incentive stock options or non-statutory stock options. Stock purchase rights may also be granted under the 2004 Equity Incentive Plan. Incentive stock options may only be granted to employees. The Board of Directors determines the period over which options become exercisable. Options granted under the Plan to employees generally vest over a four year term from the vesting commencement date and become exercisable 25% on the first anniversary of the vesting commencement date and an additional 1/48th on the last day of each calendar month until all of the shares have become exercisable. During 2012, 2011 and 2010 the officers of the Company were granted options that vest over a three year term at the rate of 1/3rd on the one year anniversary of the vesting commencement date and 1/36th thereafter.The contractual term of the options granted in 2012, 2011 and 2010 was seven years.

[1] Approved by stock holders in 2012

[2] Included in options granted and options cancelled are shares granted and cancelled in connection with the Company's Option Exchange Program in 2009.

[3] Based on the closing stock price of the Company's stock of $9.00 on December 31, 2012, $7.45 on December 30, 2011 and $8.29 on December 31, 2010.

[4] The expected term represents the period during which the Company's stock-based awards are expected to be outstanding. The estimated term is based on historical experience of similar awards, giving consideration to the contractual terms of the awards, vesting requirements, and expectation of future employee behavior, including post-vesting terminations.

[5] The risk-free interest rate is based on U.S. Treasury debt securities with maturities close to the expected term of the option as of the date of grant.

[6] Expected volatility is a 50%/50% blend of implied and historical volatility. The Company has determined that this is a more reflective measure of market conditions and a better indicator of expected volatility, than its limited historical volatility since the IPO of its common stock.

[7] The Company has not historically issued any dividends and does not expect to do so in the foreseeable future.

[8] The number of restricted stock units vested includes shares that the Company withheld on behalf of the employees to satisfy the statutory tax withholding requirements.

[9] Represents the value of the Company's stock on the date that the restricted stock units vest.

[10] On the grant date, the fair value for these vested awards was $737,000.