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CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Details) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Jan. 31, 2016 | Jan. 31, 2015 | Jan. 31, 2014 | Jan. 31, 2013
Cash and Cash Equivalents |  |  |  |
Minimum percentage of cash and cash equivalents secured by U.S. Government obligations | 80.00% | 80.00% |  |
Weighted average annual interest rate on CDs (as a percent) | 0.63% |  |  |
Cash, cash equivalents | $ 160,909,000 | $ 333,691,000 | $ 272,209,000 | $ 175,142,000
Joint Venture |  |  |  |
Cash and Cash Equivalents |  |  |  |
Cash, cash equivalents | 41,757,000 |  |  |
Short-term investments | 9,006,000 |  |  |
Held-to-maturity Securities |  |  |  |
Cash and Cash Equivalents |  |  |  |
Accrued interest on held-to-maturity securities | $ 98,000 |  |  |
Held-to-maturity Securities | Minimum |  |  |  |
Cash and Cash Equivalents |  |  |  |
Maturity period | 3 months |  |  |
Held-to-maturity Securities | Maximum |  |  |  |
Cash and Cash Equivalents |  |  |  |
Maturity period | 12 months |  |  |

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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3044-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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