Condensed Statements of Stockholders' (Deficit) Equity (Unaudited) - USD ($) $ in Thousands |
Total |
Redeemable Convertible Preferred Stock |
Common Stock |
Note Receivable from Stockholder |
Additional Paid-In Capital |
Accumulated Other Comprehensive Income (Loss) |
Accumulated Deficit |
Balances at Dec. 31, 2017 |
$ (109,001)
|
|
|
$ (208)
|
$ 6,218
|
|
$ (115,011)
|
Temporary Equity Balance, Shares at Dec. 31, 2017 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Dec. 31, 2017 |
|
$ 102,505
|
|
|
|
|
|
Common Stock Balance, Shares at Dec. 31, 2017 |
|
|
465,330
|
|
|
|
|
Exercise of common stock options |
38
|
|
|
|
38
|
|
|
Exercise of common stock options, Shares |
|
|
6,619
|
|
|
|
|
Stock-based compensation expense |
249
|
|
|
|
249
|
|
|
Vesting of early exercised shares |
14
|
|
|
|
14
|
|
|
Net loss |
(12,046)
|
|
|
|
|
|
(12,046)
|
Balances at Mar. 31, 2018 |
(120,746)
|
|
|
(208)
|
6,519
|
|
(127,057)
|
Temporary Equity Balance, Shares at Mar. 31, 2018 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Mar. 31, 2018 |
|
$ 102,505
|
|
|
|
|
|
Common Stock Balance, Shares at Mar. 31, 2018 |
|
|
471,949
|
|
|
|
|
Balances at Dec. 31, 2017 |
(109,001)
|
|
|
(208)
|
6,218
|
|
(115,011)
|
Temporary Equity Balance, Shares at Dec. 31, 2017 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Dec. 31, 2017 |
|
$ 102,505
|
|
|
|
|
|
Common Stock Balance, Shares at Dec. 31, 2017 |
|
|
465,330
|
|
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
(27)
|
|
|
|
|
|
|
Net loss |
(33,824)
|
|
|
|
|
|
|
Balances at Sep. 30, 2018 |
(141,434)
|
|
|
|
7,428
|
$ (27)
|
(148,835)
|
Temporary Equity Balance, Shares at Sep. 30, 2018 |
|
493,615,703
|
|
|
|
|
|
Temporary Equity Balance at Sep. 30, 2018 |
|
$ 187,246
|
|
|
|
|
|
Common Stock Balance, Shares at Sep. 30, 2018 |
|
|
485,097
|
|
|
|
|
Balances at Dec. 31, 2017 |
(109,001)
|
|
|
(208)
|
6,218
|
|
(115,011)
|
Temporary Equity Balance, Shares at Dec. 31, 2017 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Dec. 31, 2017 |
|
$ 102,505
|
|
|
|
|
|
Common Stock Balance, Shares at Dec. 31, 2017 |
|
|
465,330
|
|
|
|
|
Balances at Dec. 31, 2018 |
131,539
|
|
$ 23
|
|
281,891
|
(47)
|
(150,328)
|
Common Stock Balance, Shares at Dec. 31, 2018 |
|
|
22,848,184
|
|
|
|
|
Balances at Mar. 31, 2018 |
(120,746)
|
|
|
(208)
|
6,519
|
|
(127,057)
|
Temporary Equity Balance, Shares at Mar. 31, 2018 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Mar. 31, 2018 |
|
$ 102,505
|
|
|
|
|
|
Common Stock Balance, Shares at Mar. 31, 2018 |
|
|
471,949
|
|
|
|
|
Issuance of Series E redeemable convertible preferred stock, net of issuance costs |
|
$ 33,215
|
|
|
|
|
|
Exercise of common stock options |
36
|
|
|
|
36
|
|
|
Exercise of common stock options, Shares |
|
|
7,428
|
|
|
|
|
Stock-based compensation expense |
232
|
|
|
|
232
|
|
|
Net loss |
(11,541)
|
|
|
|
|
|
(11,541)
|
Balances at Jun. 30, 2018 |
(132,019)
|
|
|
(208)
|
6,787
|
|
(138,598)
|
Temporary Equity Balance, Shares at Jun. 30, 2018 |
|
173,750,421
|
|
|
|
|
|
Temporary Equity Balance at Jun. 30, 2018 |
|
$ 135,720
|
|
|
|
|
|
Common Stock Balance, Shares at Jun. 30, 2018 |
|
|
479,377
|
|
|
|
|
Issuance of Series E redeemable convertible preferred stock, net of issuance costs |
|
$ 51,526
|
|
|
|
|
|
Issuance of Series E redeemable convertible preferred stock, net of issuance costs, shares |
|
319,865,282
|
|
|
|
|
|
Exercise of common stock options and warrants |
322
|
|
|
|
322
|
|
|
Exercise of common stock options and warrants, Shares |
|
|
5,720
|
|
|
|
|
Stock-based compensation expense |
321
|
|
|
|
321
|
|
|
Vesting of early exercised shares |
(2)
|
|
|
|
(2)
|
|
|
Payment of note receivable by stockholder |
208
|
|
|
$ 208
|
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
(27)
|
|
|
|
|
(27)
|
|
Net loss |
(10,237)
|
|
|
|
|
|
(10,237)
|
Balances at Sep. 30, 2018 |
(141,434)
|
|
|
|
7,428
|
(27)
|
(148,835)
|
Temporary Equity Balance, Shares at Sep. 30, 2018 |
|
493,615,703
|
|
|
|
|
|
Temporary Equity Balance at Sep. 30, 2018 |
|
$ 187,246
|
|
|
|
|
|
Common Stock Balance, Shares at Sep. 30, 2018 |
|
|
485,097
|
|
|
|
|
Balances at Dec. 31, 2018 |
131,539
|
|
$ 23
|
|
281,891
|
(47)
|
(150,328)
|
Common Stock Balance, Shares at Dec. 31, 2018 |
|
|
22,848,184
|
|
|
|
|
Exercise of common stock options |
42
|
|
|
|
42
|
|
|
Exercise of common stock options, Shares |
|
|
8,347
|
|
|
|
|
Issuance of common stock under Employee Stock Purchase Plan |
671
|
|
|
|
671
|
|
|
Issuance of common stock under Employee Stock Purchase Plan, Shares |
|
|
68,910
|
|
|
|
|
Stock-based compensation expense |
2,286
|
|
|
|
2,286
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
103
|
|
|
|
|
103
|
|
Adoption of new accounting standards at Mar. 31, 2019 |
10,327
|
|
|
|
|
|
10,327
|
Net loss |
(14,250)
|
|
|
|
|
|
(14,250)
|
Balances at Mar. 31, 2019 |
130,718
|
|
$ 23
|
|
284,890
|
56
|
(154,251)
|
Common Stock Balance, Shares at Mar. 31, 2019 |
|
|
22,925,441
|
|
|
|
|
Balances at Dec. 31, 2018 |
131,539
|
|
$ 23
|
|
281,891
|
(47)
|
(150,328)
|
Common Stock Balance, Shares at Dec. 31, 2018 |
|
|
22,848,184
|
|
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
270
|
|
|
|
|
|
|
Net loss |
(40,955)
|
|
|
|
|
|
|
Balances at Sep. 30, 2019 |
109,906
|
|
$ 23
|
|
290,616
|
223
|
(180,956)
|
Common Stock Balance, Shares at Sep. 30, 2019 |
|
|
23,090,002
|
|
|
|
|
Balances at Mar. 31, 2019 |
130,718
|
|
$ 23
|
|
284,890
|
56
|
(154,251)
|
Common Stock Balance, Shares at Mar. 31, 2019 |
|
|
22,925,441
|
|
|
|
|
Exercise of common stock options |
10
|
|
|
|
10
|
|
|
Exercise of common stock options, Shares |
|
|
1,762
|
|
|
|
|
Stock-based compensation expense |
2,463
|
|
|
|
2,463
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
157
|
|
|
|
|
157
|
|
Net loss |
(13,793)
|
|
|
|
|
|
(13,793)
|
Balances at Jun. 30, 2019 |
119,555
|
|
$ 23
|
|
287,363
|
213
|
(168,044)
|
Common Stock Balance, Shares at Jun. 30, 2019 |
|
|
22,927,203
|
|
|
|
|
Exercise of common stock options |
81
|
|
|
|
81
|
|
|
Exercise of common stock options, Shares |
|
|
16,128
|
|
|
|
|
Issuance of common stock under Employee Stock Purchase Plan |
589
|
|
|
|
589
|
|
|
Issuance of common stock under Employee Stock Purchase Plan, Shares |
|
|
63,029
|
|
|
|
|
Vesting of restricted stock units, Shares |
|
|
114,103
|
|
|
|
|
Stock transaction associated with taxes withheld on restricted stock units |
(297)
|
|
|
|
(297)
|
|
|
Stock transaction associated with taxes withheld on restricted stock units, Shares |
|
|
(30,461)
|
|
|
|
|
Stock-based compensation expense |
2,880
|
|
|
|
2,880
|
|
|
Net unrealized gain (loss) on available-for- sale securities |
10
|
|
|
|
|
10
|
|
Net loss |
(12,912)
|
|
|
|
|
|
(12,912)
|
Balances at Sep. 30, 2019 |
$ 109,906
|
|
$ 23
|
|
$ 290,616
|
$ 223
|
$ (180,956)
|
Common Stock Balance, Shares at Sep. 30, 2019 |
|
|
23,090,002
|
|
|
|
|