Income Taxes - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Income Tax Disclosure [Abstract]
Effective tax rates	45.90%	35.50%	43.80%	37.00%
Increase in effective tax rate	10.40%		6.80%