CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 27, 2020
Jun. 29, 2019
Jun. 27, 2020
Jun. 29, 2019
Revenue:        
Revenue $ 119,023 $ 100,304 $ 220,705 $ 189,654
Cost of revenue:        
Cost of revenue 62,618 55,636 118,676 106,643
Gross profit 56,405 44,668 102,029 83,011
Operating expenses:        
Research and development 20,921 20,700 41,592 40,030
Sales and marketing 21,343 19,734 41,967 39,073
General and administrative 11,193 9,165 21,862 17,952
Restructuring charges 6,286 0 6,286 0
Total operating expenses 59,743 49,599 111,707 97,055
Loss from operations (3,338) (4,931) (9,678) (14,044)
Interest and other expense, net:        
Interest expense, net (617) (142) (907) (250)
Other income (expense), net (109) 123 (94) (268)
Total interest and other expense, net (726) (19) (1,001) (518)
Loss before provision for income taxes (4,064) (4,950) (10,679) (14,562)
Provision for income taxes 148 95 477 250
Net loss $ (4,212) $ (5,045) $ (11,156) $ (14,812)
Net loss per common share:        
Basic and diluted (in dollars per share) $ (0.07) $ (0.09) $ (0.20) $ (0.27)
Weighted-average number of shares used to compute net income (loss) per common share        
Basic (in shares) 57,261 54,624 56,906 54,339
Diluted (in shares) 57,261 54,624 56,906 54,339
Other comprehensive income, net of tax:        
Other comprehensive income (loss), net of tax - foreign currency translation adjustments, net $ 3 $ (223) $ 249 $ 43
Comprehensive loss (4,209) (5,268) (10,907) (14,769)
Systems        
Revenue:        
Revenue 110,841 92,833 205,350 175,193
Cost of revenue:        
Cost of revenue 56,721 49,561 107,429 94,162
Services        
Revenue:        
Revenue 8,182 7,471 15,355 14,461
Cost of revenue:        
Cost of revenue $ 5,897 $ 6,075 $ 11,247 $ 12,481