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STOCK-BASED COMPENSATION - Additional Information (Details) - USD ($) $ in Thousands, shares in Millions |  | 12 Months Ended
--- | --- | ---
Jan. 31, 2017 | Jan. 31, 2017 | Jan. 31, 2016 | Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Number of shares of common stock reserved for issuance | 1.2 | 1.2 |  |
Number of shares of common stock available for award | 0.4 | 0.4 |  |
Intrinsic value of the stock options exercised |  | $ 18,400 | $ 2,100 | $ 5,700
Intrinsic value of outstanding stock options | $ 24,500 | 24,500 |  |
Intrinsic value of exercisable stock options | 20,300 | 20,300 |  |
Compensation expense |  | 2,344 | 2,374 | 2,017
Unrecognized compensation cost | $ 3,100 | $ 3,100 |  |
Estimated expected life simplified method | P3Y4M6D |  |  |
Estimated expected life | P5Y6M |  |  |
Reduction in the aggregate fair value of stock option | $ 800 |  |  |
Percentage reduction in the aggregate fair value of stock option | 20.00% |  |  |
Period used for calculations |  | 5 years |  |
Company's expense for defined contribution savings plans |  | $ 1,900 | 1,500 | 1,100
Stock Options Plans |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Compensation expense |  | $ 2,300 | $ 2,400 | $ 2,000
Method used for fair value assumption |  | Black-Scholes option pricing model | Black-Scholes option pricing model | Black-Scholes option pricing model
Risk-free interest rate, minimum |  | 1.30% | 1.00% | 0.10%
Risk-free interest rate, maximum |  | 1.90% | 1.70% | 1.60%
Volatility rate, minimum |  | 33.30% | 33.90% | 29.90%
Volatility rate, maximum |  | 35.00% | 35.30% | 34.40%
ISOs | Stock Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Period to become exercisable |  | 1 year |  |
ISOs | Stock Plan | Maximum |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Incentive stock option award maximum expiration period |  | 10 years |  |
NSOs | Stock Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Period to become exercisable |  | 1 year |  |
NSOs | Stock Plan | Maximum |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |
Incentive stock option award maximum expiration period |  | 10 years |  |

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- Definition The period of monthly closing prices used for the estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Definition Description of the expected term under the specified contract (or assumed time period) the instrument will be outstanding before being exercised, placed into service or terminated, the reason and justification for its use, and the periods for which the method was used. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Discloses use of the simplified method to calculate the expected term that stock option awards under the specified plan will exist before being exercised or terminated, the reason and justification for its use, and the periods for which the method was used if it was not used in all periods presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.D.2.Q6) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition For each plan, identification of the award pricing model or other valuation method used in calculating the weighted average fair values disclosed. The model is also used to calculate the compensation expense that is shown within the balance sheet, income statement, and cash flow. Examples of valuation techniques are lattice models (binomial model), closed-form models (Black-Scholes-Merton formula), and a Monte Carlo simulation technique. Fair value is the amount at which an asset or liability could be bought or incurred or sold or settled in a current transaction between willing parties, that is, other than in a forced or liquidation sale. May include disclosures about the assumptions underlying application of the method selected. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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