Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 926,000	$ 1,005,000	$ 2,066,000	$ 1,878,000
Estimated effective tax rate	9.20%	13.00%	9.30%	11.40%
Unrecognized tax benefits	$ 3,200,000		$ 3,200,000