Stock-Based Compensation - Narrative (Details) - USD ($)		1 Months Ended		12 Months Ended
	Jun. 13, 2017	Jun. 30, 2018	Jun. 30, 2016	Dec. 31, 2019
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase offering period				6 months
Employee Stock Purchase Plan | Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)				4,632,233
Purchase price of common stock, percentage of fair market value	85.00%
Maximum stock purchase value per employee				$ 12,500
2014 Equity Incentive Plan | Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares available for grant (in shares)		3,000,000	3,900,000
Number of shares available for grant (in shares)				2,066,342