Equity (Details) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Stock options exercised, tax (benefit)	$ 103	$ (42)
Net unrealized gain on investments, tax	2	4
Net change in effective portion of hedging contracts, tax benefit	$ 46	$ 100
Common Stock Class Undefined
Common Stock, Voting Rights	Each share of common stock is entitled to one vote per share on all matters submitted to a vote of the shareholders.
Class A Common Stock
Common Stock, Voting Rights	Each share of class A common stock is entitled to 10 votes per share on all matters submitted to a vote of the shareholders.
Common stock, Conversion basis	Each share of class A common stock is entitled to 10 votes per share on all matters submitted to a vote of the shareholders. Each holder of class A common stock is entitled to convert, at any time, any and all of such shares into the same number of shares of common stock. Each share of class A common stock is converted automatically into common stock in the event that the beneficial or record ownership of such shares of class A common stock is transferred to any person, except to certain family members or affiliated persons deemed “permitted transferees” pursuant to the Company’s Restated Certificate of Incorporation as amended.