Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Jan. 31, 2014
Disclosure Income Taxes Additional Information [Abstract]
Effective tax rate	5.40%	381.00%
Period specific items benefit	$ 10
Effective income tax rate forecast	11.00%
U.S. federal statutory rate	35.00%
Income taxes associated with uncertain income tax positions	21,047
Liability for uncertain tax positions, current	372
Income tax liability	$ 20,675		$ 18,431