Stockholders' Equity (Tables)

6 Months Ended

Jul. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

A summary of stock option activity for the six months ended July 31, 2016 is as follows:

						Weighted
				Weighted		average
				average		remaining		Aggregate
	Number			exercise		contractual		intrinsic
	of shares			price		term (in years)		value
Options outstanding at January 31, 2016		18,549,702		$	5.01		6.8	$	359,306,108
Options granted		1,075,000			25.41
Options exercised		(2,006,882	)		2.27
Options forfeited/cancelled		(212,452	)		4.40
Options outstanding at July 31, 2016		17,405,368		$	6.60		6.7	$	546,431,136
Options vested and exercisable at July 31, 2016		16,731,371		$	6.54		6.7	$	526,238,982
Options vested and exercisable at July 31, 2016 and expected to vest thereafter		5,333,997		$	5.17		6.1	$	175,053,298

Summary of Restricted Stock Unit (RSU) Activity

A summary of restricted stock unit (RSU) activity for the six months ended July 31, 2016 is as follows:

				Weighted
	Unreleased			average
	Restricted			grant date
	Stock Units			fair value
Balance at January 31, 2016		2,219,425		$	26.80
RSUs granted		1,876,140			26.85
RSUs vested		(420,845	)		26.57
RSUs forfeited/cancelled		(202,939	)		26.23
Balance at July 31, 2016		3,471,781		$	26.89

Schedule of Weighted-Average Assumptions Used to Estimate Grant Date Fair Value of Options Granted

The following table presents the weighted-average assumptions used to estimate the grant date fair value of options granted during the periods presented:

	Three Months Ended July 31,			Six Months Ended July 31,
	2016	2015		2016		2015
Volatility	—	45% – 46%		45% – 46%		45% – 46%
Expected term (in years)	—	5.50 – 6.32		6.31 – 7.56		5.50 – 6.32
Risk-free interest rate	—	1.69% – 1.84%		1.48% – 1.67%		1.69% – 1.84%
Dividend yield	—		0%		0%		0%