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Stockholders' Equity - Summary of Information about Employee and Director Stock Options Outstanding and Exercisable (Detail) (USD $)
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12 Months Ended |
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Jan. 31, 2014
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Number outstanding |
1,502,176
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| Options Outstanding, Weighted average remaining contractual terms (years) |
3 years 11 months 5 days
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| Options Outstanding, Weighted average exercise price |
$ 9.77
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| Options Exercisable, Number Exercisable |
1,440,521
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| Options Exercisable, Weighted average exercise price |
$ 9.90
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Exercise Price Range One [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 6.74
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 6.74
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| Options Outstanding, Number outstanding |
224,421
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| Options Outstanding, Weighted average remaining contractual terms (years) |
4 years 11 months 16 days
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| Options Outstanding, Weighted average exercise price |
$ 6.74
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| Options Exercisable, Number Exercisable |
166,099
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| Options Exercisable, Weighted average exercise price |
$ 6.74
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Exercise Price Range Two [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 7.00
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 8.15
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| Options Outstanding, Number outstanding |
11,500
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| Options Outstanding, Weighted average remaining contractual terms (years) |
3 years 1 month 28 days
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| Options Outstanding, Weighted average exercise price |
$ 7.69
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| Options Exercisable, Number Exercisable |
8,167
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| Options Exercisable, Weighted average exercise price |
$ 7.69
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Exercise Price Range Three [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 8.22
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 8.22
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| Options Outstanding, Number outstanding |
875,000
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| Options Outstanding, Weighted average remaining contractual terms (years) |
5 years 2 months 27 days
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| Options Outstanding, Weighted average exercise price |
$ 8.22
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| Options Exercisable, Number Exercisable |
875,000
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| Options Exercisable, Weighted average exercise price |
$ 8.22
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Exercise Price Range Four [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 11.56
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 14.47
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| Options Outstanding, Number outstanding |
193,980
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| Options Outstanding, Weighted average remaining contractual terms (years) |
5 months 12 days
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| Options Outstanding, Weighted average exercise price |
$ 13.29
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| Options Exercisable, Number Exercisable |
193,980
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| Options Exercisable, Weighted average exercise price |
$ 13.29
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Exercise Price Range Five [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 15.52
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 15.84
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| Options Outstanding, Number outstanding |
84,313
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| Options Outstanding, Weighted average remaining contractual terms (years) |
1 month 6 days
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| Options Outstanding, Weighted average exercise price |
$ 15.62
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| Options Exercisable, Number Exercisable |
84,313
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| Options Exercisable, Weighted average exercise price |
$ 15.62
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Exercise Price Range Six [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 16.04
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 16.04
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| Options Outstanding, Number outstanding |
2,500
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| Options Outstanding, Weighted average remaining contractual terms (years) |
7 months 28 days
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| Options Outstanding, Weighted average exercise price |
$ 16.04
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| Options Exercisable, Number Exercisable |
2,500
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| Options Exercisable, Weighted average exercise price |
$ 16.04
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Exercise Price Range Seven [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 16.56
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 16.56
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| Options Outstanding, Number outstanding |
5,000
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| Options Outstanding, Weighted average remaining contractual terms (years) |
1 year 4 days
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| Options Outstanding, Weighted average exercise price |
$ 16.56
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| Options Exercisable, Number Exercisable |
5,000
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| Options Exercisable, Weighted average exercise price |
$ 16.56
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Exercise Price Range Eight [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 17.26
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 17.26
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| Options Outstanding, Number outstanding |
5,000
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| Options Outstanding, Weighted average remaining contractual terms (years) |
11 months 12 days
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| Options Outstanding, Weighted average exercise price |
$ 17.26
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| Options Exercisable, Number Exercisable |
5,000
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| Options Exercisable, Weighted average exercise price |
$ 17.26
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Exercise Price Range Nine [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 17.39
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 17.39
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| Options Outstanding, Number outstanding |
89,462
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| Options Outstanding, Weighted average remaining contractual terms (years) |
9 months
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| Options Outstanding, Weighted average exercise price |
$ 17.39
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| Options Exercisable, Number Exercisable |
89,462
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| Options Exercisable, Weighted average exercise price |
$ 17.39
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Exercise Price Range Ten [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Options Outstanding, Range of exercise prices, Lower Range Limit |
$ 19.98
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| Options Outstanding, Range of exercise prices, Upper Range Limit |
$ 19.98
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| Options Outstanding, Number outstanding |
11,000
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| Options Outstanding, Weighted average remaining contractual terms (years) |
1 year 7 months 21 days
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| Options Outstanding, Weighted average exercise price |
$ 19.98
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| Options Exercisable, Number Exercisable |
11,000
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| Options Exercisable, Weighted average exercise price |
$ 19.98
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