Common Stock and Employee Stock Plans - Additional Information (Details)			1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 01, 2020 shares	Mar. 28, 2019 USD ($) shares	Mar. 31, 2019	Mar. 31, 2019 USD ($) shares	Dec. 31, 2019 USD ($) vote $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Voting power percentage of total outstanding stock					50.00%
Stock options granted (in shares)					0	0
Intrinsic value of stock options exercised | $					$ 617,400,000	$ 85,000,000.0	$ 25,800,000
Fair value of common stock (in dollars per share) | $ / shares					$ 43.02	$ 47.37	$ 35.47
Issuance of common stock upon exercise of stock options (in shares)					10,856,000
Withholding tax adjustment | $					$ 942,895,000	$ 0	$ 0
Stock-based compensation expense | $					1,599,311,000	8,577,000	$ 9,546,000
Aggregate unrecognized compensation cost | $					$ 3,900,000	$ 9,600,000
Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in business combination (in shares)						241,390
Aggregate grant-date fair value | $						$ 11,400,000
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, number of votes per share | vote					1
Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, number of votes per share | vote					20
Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares reserved for future issuance (in shares)	35,000,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					41,685,376
Withholding tax adjustment (in shares)					10,777,331
Withholding tax adjustment | $					$ 719,500,000
Aggregate grant-date fair value | $					$ 1,793,305,000	2,199,554,000
Number of shares vested (in shares)					28,623,000
Aggregate grant-date fair value, weighted average period					2 years 7 months 6 days
Restricted Stock Units | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Withholding tax adjustment (in shares)		3,617,460
Withholding tax adjustment | $		$ 223,500,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant price of stock options, percentage of fair market value					100.00%
Common stock reserved for issuance (in shares)					2,957,350
Aggregate grant-date fair value, weighted average period					8 months 12 days
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $					$ 6,000,000.0	$ 1,400,000
Aggregate unrecognized compensation cost | $					$ 1,100,000,000
Aggregate grant-date fair value, weighted average period					1 year 7 months 6 days
Restricted Stock Awards | Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested (in shares)					146,373	20,989
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock upon exercise of stock options (in shares)				3,162,797		2,254,000	1,181,000
Value of stock during the period | $				$ 205,600,000
Number of shares issued in business combination (in shares)						241,000
2008 Equity Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Voting power percentage of total outstanding stock					10.00%
2008 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Voting power percentage of total outstanding stock					110.00%
2008 Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Maximum term					7 years
2008 Equity Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					75,504,222
Additional common stock reserved for issuance (in shares) | $					$ 11,836,692
2018 Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Maximum term					7 years
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					44,000,000
2019 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					80,604,678
2019 Equity Incentive Plan | Scenario, Forecast | Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of common stock outstanding	5.00%
2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					6,000,000
Percentage of earnings for purchase of common stock			15.00%	15.00%
Offering periods			12 months
Common stock purchased (in shares)					403,831
2019 Employee Stock Purchase Plan | Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares reserved for future issuance (in shares)	7,000,000
Percentage of common stock outstanding	1.00%