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, 2011	$ 1,609.3	$ 1,267.2	$ (0.6)	$ 342.7
Balance (in shares) at Jan. 31, 2011		227.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)		8.6
Common shares issued under stock plans	176.1	176.1
Stock-based compensation expense	108.8	108.8
Tax benefits from employee stock plans	24.3	24.3
Net income	285.3			285.3
Other comprehensive income (loss)	6.5		6.5
Repurchase and retirement of common shares (in shares)		(9.7)
Repurchase and retirement of common shares	(327.4)	(211.0)		(116.4)
Balances 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 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	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 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