Summary of Business and Significant Accounting Policies (Schedule of Assets Measured at Fair Value Using Significant Unobservable Inputs (Level 3)) (Details) (USD $) In Thousands	Apr. 30, 2011	Jan. 31, 2011	Jan. 31, 2010
Summary of Business and Significant Accounting Policies
Beginning balance	$ 14,400	$ 17,138	$ 0
Additions	262	17,138
Payments	(3,000)
Ending balance	$ 14,400	$ 17,138	$ 0