Equity Incentive Plans - Summary of Changes in Shares Available for Grant (Details)	12 Months Ended
	Dec. 31, 2019 shares
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, Outstanding, Beginning Balance	6,827,996,000
Shares Available for Grant, 2019 Plan reserve established	15,519,170,000
Shares Available for Grant, Options and restricted stock units granted	(4,207,301,000)
Shares Available for Grant, Options and restricted stock units forfeited or cancelled	412,357,000
Shares Available for Grant, Outstanding, Ending Balance	15,396,254,000
2009 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, 2009 Plan reserve cancelled	(3,155,968,000)