v3.6.0.2
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Changes in Accounting Policy (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Prepaid expenses and other current assets $ 5,970       $ 7,613       $ 5,970 $ 7,613    
Total current assets 121,862       134,303       121,862 134,303    
Other assets 5,100       3,680       5,100 3,680    
Total assets 136,483       147,652       136,483 147,652    
Accumulated deficit (227,257)       (190,346)       (227,257) (190,346)    
Total stockholders' equity 28,688       40,931       28,688 40,931 $ 62,916 $ (102)
Total liabilities and stockholders' equity 136,483       147,652       136,483 147,652    
Sales and marketing 18,961 $ 19,647 $ 21,322 $ 21,068 21,035 $ 21,364 $ 20,195 $ 18,495 80,998 81,089 70,846  
Operating income (loss) (7,342) (9,643) (7,441) (12,387) (7,099) (10,287) (10,593) (15,071) (36,813) (43,050) (27,045)  
Net loss (7,264) $ (9,712) $ (7,412) $ (12,523) (7,045) $ (10,562) $ (10,827) $ (15,784) $ (36,911) $ (44,218) $ (29,037)  
Net loss per share allocable to common stockholders, basic and diluted (USD per share)                 $ (0.73) $ (0.93) $ (0.80)  
Weighted-average shares used to compute net loss per share, basic and diluted                 50,332,872 47,323,253 36,097,405  
Comprehensive loss                 $ (36,881) $ (44,279) $ (29,037)  
Prepaid expenses and other current assets                 2,081 (2,485) (1,255)  
Other assets                 80 (1,024) (1,094)  
Net cash used in operating activities                 (14,554) (4,957) (8,748)  
Scenario, Previously Reported [Member]                        
Prepaid expenses and other current assets         4,129         4,129    
Total current assets         130,819         130,819    
Other assets         426         426    
Total assets         140,914         140,914    
Accumulated deficit         (197,084)         (197,084)    
Total stockholders' equity         34,193         34,193    
Total liabilities and stockholders' equity         140,914         140,914    
Sales and marketing                   83,066 72,364  
Operating income (loss)                   (45,027) (28,563)  
Net loss                   $ (46,195) $ (30,555)  
Net loss per share allocable to common stockholders, basic and diluted (USD per share)                   $ (0.98) $ (0.85)  
Weighted-average shares used to compute net loss per share, basic and diluted                   47,323,253 36,097,405  
Comprehensive loss                   $ (46,256) $ (30,555)  
Prepaid expenses and other current assets                   (1,275) (733)  
Other assets                   (257) (98)  
Net cash used in operating activities                   (4,957) (8,748)  
Restatement Adjustment [Member]                        
Prepaid expenses and other current assets 3,038               3,038      
Total current assets 118,930               118,930      
Other assets 1,985               1,985      
Total assets 130,436               130,436      
Accumulated deficit (233,304)               (233,304)      
Total stockholders' equity 22,641               22,641      
Total liabilities and stockholders' equity 130,436               130,436      
Sales and marketing                 80,307      
Operating income (loss)                 (36,122)      
Net loss                 $ (36,220)      
Net loss per share allocable to common stockholders, basic and diluted (USD per share)                 $ (0.72)      
Weighted-average shares used to compute net loss per share, basic and diluted                 50,332,872      
Comprehensive loss                 $ (36,190)      
Prepaid expenses and other current assets                 1,529      
Other assets                 (59)      
Net cash used in operating activities                 (14,554)      
Change in Accounting Principle for Sales Commissions [Member]                        
Prepaid expenses and other current assets 2,932       3,484       2,932 3,484    
Total current assets 2,932       3,484       2,932 3,484    
Other assets 3,115       3,254       3,115 3,254    
Total assets 6,047       6,738       6,047 6,738    
Accumulated deficit 6,047       6,738       6,047 6,738    
Total stockholders' equity 6,047       6,738       6,047 6,738    
Total liabilities and stockholders' equity $ 6,047       $ 6,738       6,047 6,738 4,800  
Sales and marketing                 691 (1,977) (1,518)  
Operating income (loss)                 (691) 1,977 1,518  
Net loss                 $ (691) $ 1,977 $ 1,518  
Net loss per share allocable to common stockholders, basic and diluted (USD per share)                 $ (0.01) $ 0.05 $ 0.05  
Weighted-average shares used to compute net loss per share, basic and diluted                 0 0 0  
Comprehensive loss                 $ (691) $ 1,977 $ 1,518  
Prepaid expenses and other current assets                 552 (1,210) (522)  
Other assets                 139 (767) (996)  
Net cash used in operating activities                 $ 0 $ 0 $ 0