Segment Reporting - Additional Information (Detail)	3 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Concentration Risk [Line Items]
Number of customer accounted for approximately 10% or more of total revenues	1	1
Description of external customer accounted for total revenues	one customer accounted for 20% of our total revenues	one customer accounted for 21% of our total revenues
Customer Concentration Risk [Member] | Sales Revenue, Goods and Services, Net [Member]
Concentration Risk [Line Items]
Customer percent of total revenues	20.00%	21.00%