Financial Instruments and Fair Value - Schedule of Available-for-Sale Securities at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 40,131
Unrealized Gains	9
Unrealized Losses	(10)
Fair Value	40,130
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,427
Fair Value	2,427
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,497
Fair Value	1,497
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,356
Unrealized Gains	9
Unrealized Losses	(10)
Fair Value	32,355
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,851
Fair Value	$ 3,851

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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