SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended						6 Months Ended		9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2013	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Jan. 02, 2012
Consolidated Balance Sheet
Prepaid expenses and other current assets	$ 10,391								$ 10,391		$ 8,651
Deferred income taxes (current)	79								79		30
Total current assets	177,681								177,681		214,575
Other assets	3,225								3,225		1,680
Deferred income taxes (non-current)	218								218		257
Total assets	278,926								278,926		279,446
Accumulated income (loss)	(25,444)								(25,444)		(13,158)	21,960
Total stockholders' equity	143,253								143,253		148,194
Total liabilities and stockholders' equity	278,926								278,926		279,446
Consolidated Statement of Operations
Sales and marketing	34,844	32,787	37,273	36,830	35,119	38,570	70,059	73,689	104,904	110,518
Loss from operations	(7,507)	(3,634)	(4,351)	(3,387)	(5,039)	(2,525)	(7,986)	(7,564)	(15,494)	(10,951)
Income tax provision (benefit)	(3,631)	(387)	968	28,691	(144)	(808)	580	(952)	(3,052)	27,739
Net loss	(4,169)	(3,213)	(4,904)	(32,063)	(4,554)	(2,003)	(8,117)	(6,557)	(12,286)	(38,620)
Basic net loss per share (in dollars per share)	$ (0.19)	$ (0.15)	$ (0.23)	$ (1.52)	$ (0.22)	$ (0.10)	$ (0.38)	$ (0.31)	$ (0.57)	$ (1.84)
Diluted net loss per share (in dollars per share)	$ (0.19)	$ (0.15)	$ (0.23)	$ (1.52)	$ (0.22)	$ (0.10)	$ (0.38)	$ (0.31)	$ (0.57)	$ (1.84)
Shares used in computing basic net loss per share	21,827	21,569	21,360	21,073	20,995	20,942	21,465	20,969	21,587	21,004
Shares used in computing diluted net loss per share	21,827	21,569	21,360	21,073	20,995	20,942	21,465	20,969	21,587	21,004
Consolidated Statement of Comprehensive Loss
Net loss	(4,169)	(3,213)	(4,904)	(32,063)	(4,554)	(2,003)	(8,117)	(6,557)	(12,286)	(38,620)
Other comprehensive income (loss)	(3,796)	(3,093)	(5,385)	(31,828)	(4,863)	(1,701)	(8,478)	(6,564)	(12,274)	(38,392)
Consolidated Statement of Cash Flows
Net loss	(4,169)	(3,213)	(4,904)	(32,063)	(4,554)	(2,003)	(8,117)	(6,557)	(12,286)	(38,620)
Deferred income tax provision (benefit)			289			(1,380)	(623)	(1,206)	(4,527)	25,846
Prepaid expenses and other current assets			(2,446)			621	(2,744)	789	(1,593)	662
Other assets			105			(1,161)	42	(1,045)	(1,662)	(78)
Net cash provided by (used in) operating activities			(5,635)			2,656	(3,147)	6,068	(3,734)	11,492
As Previously Reported
Consolidated Balance Sheet
Prepaid expenses and other current assets											5,204
Deferred income taxes (current)											79
Total current assets											211,177
Other assets											1,484
Deferred income taxes (non-current)											260
Total assets											275,855
Accumulated income (loss)											(16,749)	19,082
Total stockholders' equity											144,603
Total liabilities and stockholders' equity											275,855
Consolidated Statement of Operations
Sales and marketing		33,144	37,060	37,113	35,125	38,404	70,203	73,529		110,641
Loss from operations		(3,991)	(4,138)	(3,670)	(5,045)	(2,359)	(8,130)	(7,404)		(11,074)
Income tax provision (benefit)		(400)	977	29,735	(160)	(742)	576	(902)		28,833
Net loss		(3,557)	(4,700)	(33,390)	(4,544)	(1,903)	(8,257)	(6,447)		(39,837)
Basic net loss per share (in dollars per share)		$ (0.16)	$ (0.22)	$ (1.58)	$ (0.22)	$ (0.09)	$ (0.38)	$ (0.31)		$ (1.90)
Diluted net loss per share (in dollars per share)		$ (0.16)	$ (0.22)	$ (1.58)	$ (0.22)	$ (0.09)	$ (0.38)	$ (0.31)		$ (1.90)
Shares used in computing basic net loss per share		21,569	21,360	21,073	20,995	20,942	21,465	20,969		21,004
Shares used in computing diluted net loss per share		21,569	21,360	21,073	20,995	20,942	21,465	20,969		21,004
Consolidated Statement of Comprehensive Loss
Net loss		(3,557)	(4,700)	(33,390)	(4,544)	(1,903)	(8,257)	(6,447)		(39,837)
Other comprehensive income (loss)		(3,437)	(5,181)	(33,155)	(4,853)	(1,601)	(8,618)	(6,454)		(39,609)
Consolidated Statement of Cash Flows
Net loss		(3,557)	(4,700)	(33,390)	(4,544)	(1,903)	(8,257)	(6,447)		(39,837)
Deferred income tax provision (benefit)			298			(1,314)	(627)	(1,156)		26,940
Prepaid expenses and other current assets			(2,559)			503	(2,568)	649		785
Other assets			5			(1,209)	10	(1,065)		(78)
Net cash provided by (used in) operating activities			(5,635)			2,656	(3,147)	6,068		11,492
Computed under Prior Method
Changes in Accounting Principle
Book to tax basis difference related to commission expense	0								0
Consolidated Balance Sheet
Prepaid expenses and other current assets	6,457								6,457
Deferred income taxes (current)	141								141
Total current assets	173,809								173,809
Other assets	3,060								3,060
Deferred income taxes (non-current)	221								221
Total assets	274,892								274,892
Accumulated income (loss)	(29,478)								(29,478)
Total stockholders' equity	139,219								139,219
Total liabilities and stockholders' equity	274,892								274,892
Consolidated Statement of Operations
Sales and marketing	35,156								105,360
Loss from operations	(7,819)								(15,950)
Income tax provision (benefit)	(3,640)								(3,065)
Net loss	(4,472)								(12,729)
Basic net loss per share (in dollars per share)	$ (0.20)								$ (0.59)
Diluted net loss per share (in dollars per share)	$ (0.20)								$ (0.59)
Shares used in computing basic net loss per share	21,827								21,587
Shares used in computing diluted net loss per share	21,827								21,587
Consolidated Statement of Comprehensive Loss
Net loss	(4,472)								(12,729)
Other comprehensive income (loss)	(4,099)								(12,717)
Consolidated Statement of Cash Flows
Net loss	(4,472)								(12,729)
Deferred income tax provision (benefit)									(4,539)
Prepaid expenses and other current assets									(1,106)
Other assets									(1,694)
Net cash provided by (used in) operating activities									(3,734)
Computed under Prior Method | Impact of Commission Adjustment
Consolidated Balance Sheet
Prepaid expenses and other current assets	3,934								3,934		3,447
Deferred income taxes (current)	(62)								(62)		(49)
Total current assets	3,872								3,872		3,398
Other assets	165								165		196
Deferred income taxes (non-current)	(3)								(3)		(3)
Total assets	4,034								4,034		3,591
Accumulated income (loss)	4,034								4,034		3,591	2,878
Total stockholders' equity	4,034								4,034		3,591
Total liabilities and stockholders' equity	4,034								4,034		3,591
Consolidated Statement of Operations
Sales and marketing	(312)	(357)	213	(283)	(6)	166	(144)	160	(456)	(123)
Loss from operations	312	357	(213)	283	6	(166)	144	(160)	456	123
Income tax provision (benefit)	9	13	(9)	(1,044)	16	(66)	4	(50)	13	(1,094)
Net loss	303	344	(204)	1,327	(10)	(100)	140	(110)	443	1,217
Basic net loss per share (in dollars per share)	$ 0.01	$ 0.01	$ (0.01)	$ 0.06	$ 0.00	$ (0.01)			$ 0.02	$ 0.06
Diluted net loss per share (in dollars per share)	$ 0.01	$ 0.01	$ (0.01)	$ 0.06	$ 0.00	$ (0.01)			$ 0.02	$ 0.06
Consolidated Statement of Comprehensive Loss
Net loss	303	344	(204)	1,327	(10)	(100)	140	(110)	443	1,217
Other comprehensive income (loss)	303	344	(204)	1,327	(10)	(100)	140	(110)	443	1,217
Consolidated Statement of Cash Flows
Net loss	303	344	(204)	1,327	(10)	(100)	140	(110)	443	1,217
Deferred income tax provision (benefit)			(9)			(66)	4	(50)	12	(1,094)
Prepaid expenses and other current assets			113			118	(176)	140	(487)	(123)
Other assets			$ 100			$ 48	$ 32	$ 20	$ 32