Related Party Transactions (Details) (USD $)	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Related Party Transactions
Revenue from sales to the related party	$ 2,000,000	$ 1,600,000	$ 500,000
Accounts receivable from the related party	0	1,200,000
Expenses related to purchases from the related party	900,000	300,000	200,000
Accounts payable to related party	$ 0	$ 0