Note 14 - Employee Stock Option and Retirement Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands | Feb. 03, 2014 | Nov. 01, 2013 | Jan. 31, 2017 | Nov. 30, 2015 | Feb. 28, 2015 | Jul. 31, 2012 | May 31, 2017 | Feb. 28, 2017 | Nov. 30, 2016 | Sep. 30, 2016 | Aug. 31, 2016 | May 31, 2016 | Feb. 29, 2016 | Nov. 30, 2015 | Feb. 28, 2015 | May 31, 2017 | May 31, 2016 | May 31, 2017 |
Share Price | | | | | | | $ 165.69 | | | | | | $ 178.03 | | | | | $ 165.69 | | $ 165.69 |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent | | | | | | | | | | | | | | | | | | 85.00% | | |
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate | | | | | | | 10.00% | | | | | | | | | | | 10.00% | | 10.00% |
Stock Issued During Period, Shares, Employee Stock Purchase Plans | | | | | | | 17,314 | | | | | | | 17,538 | | | | 54,554 | 53,711 | |
Treasury Stock Acquired, Average Cost Per Share | | | | | | | $ 140.84 | | | | | | | $ 131.57 | | | | $ 137.38 | $ 129.83 | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | | 353,990 | | | | | | | | | | | 353,990 | | 353,990 |
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent | | | | | | | | | | 60.00% | | | | | | | | | | |
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay | | | | | | | | | | 4.00% | | | | | | | | | | |
Defined Contribution Plan, Employer Matching Contribution, Vesting Period | | | | | | | | | | 5 years | | | | | | | | | | |
Defined Contribution Plan, Employer Discretionary Contribution Amount | | | | | | | | | | | | | | | | | | $ 7,300 | $ 7,100 | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | | | | | | | $ 163.05 | | | | | | | 152.10 | | | | $ 154.01 | $ 168.51 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | | | | | | | 3,597,000 | 3,699,000 | | 3,833,000 | | | 3,364,000 | | | | | 3,597,000 | | 3,597,000 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | | | | | | | $ 139.97 | $ 139.27 | | $ 136.43 | | | $ 129.54 | | | | | $ 139.97 | | $ 139.97 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | $ 76,100 | | | | | | | | | | | $ 76,100 | | $ 76,100 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 3 years 109 days | | |
The 2004 Stock Option and Award Plan [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | | | | | | | | | | | | | | | | | | $ 34,800 | $ 43,000 | |
Employee Stock Option [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | | | | | | | $ 163.05 | $ 169.16 | | $ 152.51 | | | | $ 152.10 | $ 150.81 | | | | | |
Employee Stock Option [Member] | The 2004 Stock Option and Award Plan [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | | | | | | | $ 97.20 | | | | | | $ 89.42 | | | | | $ 97.20 | | $ 97.20 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | | | | | | | $ 57,100 | | | | | | $ 86,000 | | | | | $ 57,100 | | $ 57,100 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | | | | | | | | | 767,071 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | | | | | | | | | | | | | | | | | 5 years | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | | | | | | | | | | | | | | | | | | $ 154.01 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | | | | | | | 3,597,101 | | | | | | | | | | | 3,597,101 | | 3,597,101 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | | | | | | | $ 139.97 | | | | | | | | | | | $ 139.97 | | $ 139.97 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | $ 58,600 | | | | | | | | | | | $ 58,600 | | $ 58,600 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 3 years 146 days | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | | | | | | | 800,000 | | | | | | 1,000,000 | | | | | 800,000 | | 800,000 |
Employee Stock Option [Member] | The 2004 Stock Option and Award Plan [Member] | Minimum [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | | | | | | | | | | | | | | | | | 7 years | | |
Employee Stock Option [Member] | The 2004 Stock Option and Award Plan [Member] | Maximum [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | | | | | | | | | | | | | | | | | 10 years | | |
Performance Shares [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | 241,546 | | 61,744 | | 22,460 | | | | | | 530,418 | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | 20.00% | | | | | | | | | | | | | | 80.00% |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares | | | | | | | | | | | | | | | | | | | | 193,256 |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | | | | | | | | $ 169.16 | | $ 159.45 | | | | | | | | | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | $ 100 | | | | | | | | | | | $ 100 | | $ 100 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 73 days | | |
Performance Shares [Member] | Code Red, Inc. [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | | | | | | | | 137,522 | | | |
Performance Shares [Member] | Code Red, Inc. [Member] | Share-based Compensation Award, Tranche One [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | | | | | | | | 68,761 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | | | | | | | | | | | | 70.00% | | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | 900 | | | | | | | | | | | $ 900 | | 900 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 1 year 255 days | | |
Performance Shares [Member] | Code Red, Inc. [Member] | Share-based Compensation Award, Tranche Two [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | | | | | | | | 68,761 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | | | | | | | | | | | | | | | | 4 years | | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | $ 500 | | | | | | | | | | | $ 500 | | $ 500 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 1 year 255 days | | |
Performance Shares [Member] | Portware LLC [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | | | | 20,911 | | | 530,418 | | | | |
Performance Shares [Member] | Portware LLC [Member] | Share-based Compensation Award, Tranche One [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | | | | | | | 40.00% | | | | 40.00% | | 0.00% | | |
Performance Shares [Member] | Portware LLC [Member] | Share-based Compensation Award, Tranche Two [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | | | | | | | 20.00% | | | | 20.00% | | 50.00% | | |
Performance Shares [Member] | Portware LLC [Member] | Share-based Compensation Award, Tranche Four [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | | | | | | | | | | | | | 100.00% | | |
Performance Shares [Member] | Portware LLC [Member] | Share-based Compensation Award, Tranche Three [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | | | | | | | | | | | | | 70.00% | | |
Performance Shares [Member] | Vermilion Holdings Limited [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | 61,744 | | | | | | | | | | | | | | | | | |
Performance Shares [Member] | Vermilion Holdings Limited [Member] | Share-based Compensation Award, Tranche One [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 40.00% | | | | | | | | | | | | | | | | | |
Performance Shares [Member] | Vermilion Holdings Limited [Member] | Share-based Compensation Award, Tranche Two [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 20.00% | | | | | | | | | | | | | | | | | |
Performance Shares [Member] | Vermilion Holdings Limited [Member] | Share-based Compensation Award, Tranche Four [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 20.00% | | | | | | | | | | | | | | | | | |
Performance Shares [Member] | Vermilion Holdings Limited [Member] | Share-based Compensation Award, Tranche Three [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 20.00% | | | | | | | | | | | | | | | | | |
Restricted Stock [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period | | | | | | | | 6,000 | [1] | 95,000 | [2] | | | | | | | 101,234 | 51,762 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | | | | | | | | 8,000 | | 5,000 | | | | | | | | 12,927 | 93,375 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | | | | | | | | $ 161.31 | | $ 151.63 | | | | | | | | $ 157.50 | $ 159.42 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share Equivalent | | | | | | | 2.5 | | | | | | | | | | | 2.5 | | 2.5 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number | | | | | | | 168,000 | 171,000 | | 172,000 | | | 262,000 | | | | | 168,000 | | 168,000 |
Restricted Stock [Member] | The 2004 Stock Option and Award Plan [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period | | | | | | | | 6,357 | | 94,877 | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 5,150 | 73,522 | | | | | | | | | | | | | | | | 12,927 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | | | | | | | | | | | | | | | | | | $ 157.50 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 5 years | | | | | | | | | | | | | | | | | 5 years | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 40.00% | | | | 100.00% | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number | | | | | | | 168,096 | | | | | | | | | | | 168,096 | | 168,096 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | | | | | | | $ 17,500 | | | | | | | | | | | $ 17,500 | | $ 17,500 |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | | | | | | | | | 2 years 328 days | | |
Restricted Stock [Member] | The 2004 Stock Option and Award Plan [Member] | Share-based Compensation Award, Tranche One [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | 5 years | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 40.00% | | | | | | | | | | | | | | | | | | |
Restricted Stock [Member] | The 2004 Stock Option and Award Plan [Member] | Share-based Compensation Award, Tranche Two [Member] | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | 20.00% | | | | | | | | | | | | | | | | |
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[1] | Of the 6,357 restricted stock awards that vested during the second quarter of fiscal 2017, 5,150 related to awards granted on February 3, 2014. The remaining 40% of these restricted stock awards cliff vest after five years on February 3, 2019 and are amortized to expense over the vesting period using the straight-line attribution method. The other restricted stock awards that vested related to awards granted in February 2015 in connection with the Code Red acquisition, which vested 100% on February 9, 2017. |
[2] | Of the 94,877 restricted stock awards that vested during the first quarter of fiscal 2017, 73,522 related to awards granted on November 1, 2013. The remaining 40% of these restricted stock awards cliff vest after five years on November 1, 2018 and are amortized to expense over the vesting period using the straight-line attribution method. The other restricted stock awards that vested related primarily to awards granted in November 2015, which vest 20% per year on the anniversary date of the award. |