Shareholder Report, Average Annual Return (Details)
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12 Months Ended |
60 Months Ended |
112 Months Ended |
120 Months Ended |
Jul. 31, 2026 |
Jul. 31, 2026 |
Jul. 31, 2026 |
Jul. 31, 2026 |
| C000018473 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class A with load
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| Average Annual Return, Percent |
26.58%
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0.53%
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12.40%
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| C000018475 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class C with load
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| Average Annual Return, Percent |
32.13%
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0.95%
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12.20%
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| C000054855 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class F
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| C000188220 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class F3
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| C000018477 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class I
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| C000018476 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class P
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| C000054856 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class R2
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| C000054857 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class R3
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| C000151972 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class R4
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| C000151973 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class R5
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| C000151974 |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Class R6
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| Without Sales Load [Member] | C000018473 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.29%
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1.72%
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13.06%
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| Without Sales Load [Member] | C000018475 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
33.13%
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0.95%
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12.20%
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| Without Sales Load [Member] | C000054855 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.50%
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1.87%
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13.23%
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| Without Sales Load [Member] | C000188220 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.67%
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2.07%
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13.79%
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| Without Sales Load [Member] | C000018477 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.58%
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1.97%
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13.35%
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| Without Sales Load [Member] | C000018476 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
33.97%
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1.51%
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12.88%
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| Without Sales Load [Member] | C000054856 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
33.75%
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1.36%
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12.67%
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| Without Sales Load [Member] | C000054857 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
33.89%
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1.47%
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12.78%
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| Without Sales Load [Member] | C000151972 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.25%
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1.72%
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13.07%
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| Without Sales Load [Member] | C000151973 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.58%
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1.97%
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13.35%
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| Without Sales Load [Member] | C000151974 |
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| Average Annual Return [Line Items] |
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| Average Annual Return, Percent |
34.67%
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2.07%
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13.45%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.06%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: S&P 500 Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
S&P 500 Index
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| Average Annual Return, Percent |
19.56%
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12.86%
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15.08%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.24%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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| Lord Abbett Index: Russell 2000 Growth Index |
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| Average Annual Return [Line Items] |
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| Line Graph and Table Measure Name |
Russell 2000 Growth Index
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| Average Annual Return, Percent |
28.42%
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5.07%
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10.59%
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