Short-Term Investments (Tables)

9 Months Ended

Oct. 31, 2014

Investments Debt And Equity Securities [Abstract]

Schedule of Short-Term Investments

At October 31, 2014, short-term investments consisted of the following (in thousands):

			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Available-for-sale securities:
Asset-backed securities	$	8,961	$	—	$	(2	)	$	8,959
Corporate notes and bonds		50,356		8		(28	)		50,336
U.S. agency obligations		190,170		61		(6	)		190,225
U.S. treasury securities		11,199		12		—			11,211
Total available-for-sale securities	$	260,686	$	81	$	(36	)	$	260,731

At January 31, 2014, short-term investments consisted of the following (in thousands):

			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Available-for-sale securities:
Corporate notes and bonds	$	10,499	$	9	$	(1	)	$	10,507
U.S. agency obligations		15,111		7		—			15,118
Total available-for-sale securities	$	25,610	$	16	$	(1	)	$	25,625

Summary of Estimated Fair Value of Short-Term Investments, Designated as Available-for-Sale and Classified by Contractual Maturity

The following table summarizes the estimated fair value of our short-term investments, designated as available-for-sale and classified by the contractual maturity date of the securities as of the dates shown (in thousands):

	October 31,		January 31,
	2014		2014
Due in one year or less	$	176,608	$	17,667
Due in greater than one year		84,123		7,958
Total	$	260,731	$	25,625

Schedule of Fair Values and Gross Unrealized Losses of Available-for-Sale Securities Aggregated by Investment Category

The following table shows the fair values and the gross unrealized losses of these available-for-sale securities aggregated by investment category as of October 31, 2014 (in thousands):

			Gross
	Fair		Unrealized
	Value		Losses
Asset-backed securities	$	6,754	$	(2	)
Corporate notes and bonds		33,490		(28	)
U.S. agency obligations		34,215		(6	)

The following table shows the fair values and the gross unrealized losses of these available-for-sale securities aggregated by investment category as of January 31, 2014 (in thousands):

			Gross
	Fair		Unrealized
	Value		Losses
Corporate notes and bonds	$	1,403	$	(1	)