Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013	Jan. 31, 2014
Disclosure Income Taxes Additional Information [Abstract]
Income tax expense	$ 3,849	$ 3,634	$ 1,907	$ 1,864
Effective tax rate	15.80%	12.60%	5.70%	3.70%
Period specific items benefit			(2,447)
Effective income tax rate forecast			11.00%
U.S. federal statutory rate			35.00%
Income taxes associated with uncertain income tax positions	18,418		18,418
Liability for uncertain tax positions, current	245		245
Income tax liability	$ 18,173		$ 18,173		$ 18,431