XML 22 R25.htm IDEA: XBRL DOCUMENT

Financial Assets Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013	Apr. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	$ 364,709	$ 378,071	$ 208,287
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	187,288	203,361	119,007
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	177,421	170,380	84,950
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis		4,330	4,330
Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	153,376	152,775	87,750
Corporate Bonds \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	153,376	152,775	87,750
Municipal And Pre-Refunded Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	126,594	116,364	55,529
Municipal And Pre-Refunded Municipal Bonds \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	126,594	116,364	55,529
Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	42,345	43,235	21,840
Certificates of Deposit \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	42,345	43,235	21,840
US Treasury Bill Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	21,731	41,105	24,643
US Treasury Bill Securities \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	21,731	41,105	24,643
US Government Corporations and Agencies Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	11,844	9,481	6,614
US Government Corporations and Agencies Securities \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	11,844	9,481	6,614
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	8,482	10,781	7,581
Commercial Paper \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	8,482	10,781	7,581
Mutual funds, held in rabbi trust
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	337
Mutual funds, held in rabbi trust \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis	337
Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis		4,330	4,330
Auction Rate Securities \| Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets accounted for at fair value on a recurring basis		$ 4,330	$ 4,330

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details