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Income Taxes - Additional Information (Detail)
3 Months Ended 9 Months Ended
Oct. 31, 2015
Oct. 31, 2014
Oct. 31, 2015
Oct. 31, 2014
Income Tax Disclosure [Abstract]        
Effective tax rates 48.10% 45.90% 42.20% 43.80%
Increase (decrease) in effective tax rate 2.20%   (1.60%)