CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, unless otherwise specified	Total	Common stock and additional paid-in capital	Accumulated other comprehensive (loss) income	Retained earnings
Balance at Jan. 31, 2012	$ 1,882.9	$ 1,365.4	$ 5.9	$ 511.6
Balance (in shares) at Jan. 31, 2012		225.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)		10.2
Common shares issued under stock plans	220.2	220.2
Stock-based compensation expense	139.8	139.8
Tax benefits from employee stock plans	(4.3)	(4.3)
Net income	247.4			247.4
Other comprehensive loss income (loss)	(11.6)		(11.6)
Repurchase and retirement of common shares (in shares)		(12.5)
Repurchase and retirement of common shares	(431.2)	(271.3)		(159.9)
Balances at Jan. 31, 2013	2,043.2	1,449.8	(5.7)	599.1
Balance (in shares) at Jan. 31, 2013		223.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)		13.6
Common shares issued under stock plans	288.2	288.2
Stock-based compensation expense	132.2	132.2
Tax benefits from employee stock plans	(12.2)	(12.2)
Net income	228.8			228.8
Other comprehensive loss income (loss)	5.1		5.1
Repurchase and retirement of common shares (in shares)		(10.5)
Repurchase and retirement of common shares	(423.8)	(220.7)		(203.1)
Balances at Jan. 31, 2014	2,261.5	1,637.3	(0.6)	624.8
Balance (in shares) at Jan. 31, 2014	226.7	226.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)		7.2
Common shares issued under stock plans	135.4	135.4
Stock-based compensation expense	165.6	165.6
Net income	81.8			81.8
Other comprehensive loss income (loss)	(52.7)		(52.7)
Repurchase and retirement of common shares (in shares)		(6.9)
Repurchase and retirement of common shares	(372.4)	(165.2)		(207.2)
Balances at Jan. 31, 2015	$ 2,219.2	$ 1,773.1	$ (53.3)	$ 499.4
Balance (in shares) at Jan. 31, 2015	227.0	227.0