CONSOLIDATED STATEMENT OF REDEEMABLE CONVERTIBLE AND CONVERTIBLE PREFERRED STOCK
$ in Thousands
3 Months Ended
Mar. 31, 2018
USD ($)
shares
Increase (Decrease) in Redeemable Convertible and Convertible Preferred Stock  
Beginning balance $ 334,714
Exercise of stock options 976
Ending balance 374,842
Redeemable convertible preferred stock  
Increase (Decrease) in Redeemable Convertible and Convertible Preferred Stock  
Beginning balance $ 333,204
Beginning balance (in shares) | shares 88,741,194
Accretion of redeemable convertible preferred stock to redemption value $ 40,039
Ending balance $ 373,243
Ending balance (in shares) | shares 88,741,194
Series A convertible preferred stock  
Increase (Decrease) in Redeemable Convertible and Convertible Preferred Stock  
Beginning balance $ 1,510
Beginning balance (in shares) | shares 3,851,806
Exercise of stock options $ 89
Exercise of stock options (in shares) | shares 185,063
Ending balance $ 1,599
Ending balance (in shares) | shares 4,036,869