Segment Reporting - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Oct. 31, 2011 Person	Oct. 31, 2010 Person	Oct. 31, 2011 Person	Oct. 31, 2010 Person
Segment Reporting Information [Line Items]
Number of customer accounted for approximately 10% or more of total revenues	0	1	1	0
Description of external customer accounted for total revenues	no single customer accounted for 10% or more of total revenues.	one customer accounted for 10% of our total revenues.	one customer accounted for 13% of total revenues.	no single customer accounted for 10% or more of our total revenues.