Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Schedule of assumptions used for fair value of warrants

The fair value of the warrants was based on the following assumptions using the Black-Scholes option-pricing model:

	Year Ended December 31,
		2016					2015
Risk-free interest rate		1.13	%	to	1.98	%	1.51	%	to	2.03	%
Contractual life (years)		5.3		to	6.3		6.3		to	7.2
Expected volatility		46.7	%	to	48.8	%	47.8	%	to	54.2	%
Dividend yield		—					—

Schedule of reserve for unissued shares of common stock

The amount of such shares of the Company’s common stock reserved for these purposes at December 31, 2017 is as follows:

	Number of Shares
Outstanding stock options	16,714,216
Outstanding restricted stock units	4,284,438
Outstanding common stock warrants	1,458,979
Additional shares available for grant under equity plan	2,323,819
Total	24,781,452