Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Future Issuances

The Company has reserved the following shares of common stock for future issuances (in thousands):

	As of
	September 30, 2019
Common stock awards granted under equity incentive plans		16,189
Common stock awards available for issuance under Employee Stock Purchase Plan		2,089
Common stock awards available for issuance under the 2017 Equity Incentive Plan		17,317
Total reserved shares of common stock		35,595

Summary of Stock-based Compensation Expense

The following table shows total stock-based compensation expense for the three and nine months ended September 30, 2019 and 2018 (in thousands):

	Three Months Ended				Nine Months Ended
	September 30, 2019		September 30, 2018		September 30, 2019		September 30, 2018
Cost of platform revenue	$	120	$	29	$	238	$	67
Cost of player revenue		287		136		776		247
Research and development		10,230		5,561		28,020		10,658
Sales and marketing		6,415		3,277		16,555		5,673
General and administrative		5,566		2,496		13,564		4,592
Total stock-based compensation	$	22,618	$	11,499	$	59,153	$	21,237

Schedule of Stock Option Activity

The summary of the Company’s stock option activity is as follows (in thousands, except price per share data):

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)		Weighted Average Grant Date Fair Value Per Share		Aggregate Intrinsic Value
Balance, December 31, 2018 - outstanding		16,371		$	8.59				—
Granted		570			99.95			$	39.21
Exercised		(4,690	)		5.37				—
Forfeited and expired		(427	)		8.05				—
Balance, September 30, 2019 - outstanding		11,824		$	14.28		6.4		—	$	1,034,409
Options exercisable at September 30, 2019		6,538		$	5.44		5.1		—	$	629,790

Summary of Assumptions Used to Value Stock-Based Awards Granted

The fair value of options granted under the equity incentive plans is estimated on the grant date using the Black-Scholes option-valuation model. The assumptions used in the Black-Scholes model are as follows:

	Three Months Ended				Nine Months Ended
	September 30, 2019		September 30, 2018		September 30, 2019		September 30, 2018
Dividend rate		—		—		—		—
Expected term (in years)	5.0 - 6.73		5.8 - 6.8		5.0 - 6.73		5.3 - 6.8
Risk-free interest rate	1.35 - 1.79%		2.76 - 2.81%		1.35 - 2.56%		2.32 - 2.88%
Expected volatility	35 - 36%		38 - 40%		35 - 36%		38 - 40%

Summary of Restricted Stock Unit Activity

Pursuant to the 2017 Plan, the Company grants restricted stock units to employees. The fair value of restricted stock units is based on the Company’s closing stock price on the date of grant. The summary of the Company’s restricted stock unit activity is as follows (in thousands, except price per share data):

	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Balance, December 31, 2018 - outstanding		3,686		$	48.50
Awarded		1,719			74.06
Released		(595	)		47.36
Forfeited		(445	)		50.50
Balance, September 30, 2019 - outstanding		4,365		$	58.52