Stock-Based Compensation and Employee Benefit Plan - Equity Incentive Plan (Additional Information) (Details) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	24,198,742	27,949,582
Weighted average exercise price, outstanding options (in dollars per share)	$ 20.76	$ 20.76
2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	10,545,571	16,638,850
Weighted average exercise price, outstanding options (in dollars per share)	$ 27.28
2012 Equity Incentive Plan | Class B common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	9,191,693
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	12,057,826	9,454,578
Weighted average exercise price, outstanding options (in dollars per share)	$ 9.16
Shares reserved for future issuance (in shares)	19,987,416	17,233,144
2018 Equity Incentive Plan | Class A common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	5,817,989
RSUs | 2012 Equity Incentive Plan | Class B common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	1,353,878
RSUs | 2018 Equity Incentive Plan | Class A common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares)	6,239,837