Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012	Jan. 31, 2013
Disclosure Income Taxes Additional Information [Abstract]
Effective tax rate	(10.90%)	(18.70%)	(8.20%)	(4.60%)
Period specific items benefit			$ (4,521)
Effective income tax rate forecast			10.00%
U.S. federal statutory rate			35.00%
Income taxes associated with uncertain income tax positions	24,307		24,307
Liability for uncertain tax positions, current	5,782		5,782
Income tax liability	$ 18,525		$ 18,525		$ 22,663