CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Common Class A [Member]
Dividends declared, per share (in dollars per share)	$ 0.58	$ 0.26	$ 0.21
Common Class B [Member]
Dividends declared, per share (in dollars per share)	$ 0.48	$ 0.22	$ 0.20