Stockholders' Equity (Tables)

3 Months Ended

Apr. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

A summary of stock option activity for the three months ended April 30, 2014 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, 2014		25,424,437		$	3.22		8.5	$	726,649,586
Options Granted		300,000			32.26
Options Exercised		(1,392,113	)		0.49			$	30,842,309
Options Forfeited/Cancelled		(153,950	)		5.48
Options outstanding at April 30, 2014		24,178,374		$	3.73		8.1	$	379,453,926
Options vested and exercisable at April 30, 2014		4,362,659		$	0.80		6.5	$	80,302,465
Options vested and exercisable at April 30, 2014 and expected to vest thereafter		22,566,905		$	3.67		8.1	$	355,302,503

Summary of Restricted Stock Unit (RSU) Activity

A summary of restricted stock unit (RSU) activity for the three months ended April 30, 2014 is as follows:

				Weighted
	Unreleased			average
	Restricted			grant date
	Stock Units			fair value
Unreleased RSUs at January 31, 2014		156,050		$	36.52
RSUs Granted		183,775			27.17
RSUs Forfeited		(5,400	)		34.98
Unreleased RSUs at April 30, 2014		334,425		$	31.41

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

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

	Three Months Ended April 30,
	2014			2013
Volatility		48	%		42	%
Expected life (in years)		6.27			6.32 – 8.23
Risk-free interest rate		1.85	%		1.03% – 1.65	%
Dividend yield		—	%		—	%

Schedule of Weighted-Average Assumptions Used to Calculate Out Stock-Based Compensation for Each Stock Purchase under ESPP

The following table presents the weighted-average assumptions used to calculate out stock-based compensation for each stock purchase under the ESPP:

	Three Months Ended
	April 30, 2014
Volatility		44	%
Expected life (in years)		0.58
Risk-free interest rate		0.10	%
Dividend yield		—	%