CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, except Share data	Total	Common stock and additional paid-in-capital	Comprehensive Income	Accumulated other comprehensive income (loss)	Retained earnings	Total stockholders' equity
Balance at Jan. 31, 2009		$ 1,080.4		$ (11.2)	$ 241.5	$ 1,310.7
Balance (in shares) at Jan. 31, 2009		226,400,000
Common shares issued under stock award and stock purchase plans, Shares		5,200,000		0	0	70,400,000
Common shares issued under stock award and stock purchase plans, Value		70.4
Compensation expense related to stock options		93.6				93.6
Tax benefits from employee stock plans		(3.7)				(3.7)
Net income	58.0		58.0		58.0	58.0
Net loss on derivative instruments, net of taxes			2.5
Change in net unrealized gain on marketable securities, net of tax			1.5
Change in unfunded portion of pension plans			(5.9)
Net change in cumulative foreign currency translation loss			9.6
Other Comprehensive Income (Loss), Net of Tax			7.7	7.7		7.7
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			65.7
Stock Repurchased and Retired During Period, Shares	(2,700,000)	(2,700,000)
Stock Repurchased and Retired During Period, Value		(36.4)			(26.8)	(63.2)
Balances at Jan. 31, 2010		1,204.3		(3.5)	272.7	1,473.5
Balance (in shares) at Jan. 31, 2010		228,900,000
Common shares issued under stock award and stock purchase plans, Shares		7,100,000
Common shares issued under stock award and stock purchase plans, Value		120.9				120.9
Compensation expense related to stock options		80.7				80.7
Tax benefits from employee stock plans		(0.4)				(0.4)
Net income	212.0		212.0		212.0	212.0
Net loss on derivative instruments, net of taxes			(3.1)
Change in net unrealized gain on marketable securities, net of tax			0.9
Change in unfunded portion of pension plans			(3.9)
Net change in cumulative foreign currency translation loss			9.0
Other Comprehensive Income (Loss), Net of Tax			2.9	2.9		2.9
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			214.9
Stock Repurchased and Retired During Period, Shares	(9,000,000)	(9,000,000)
Stock Repurchased and Retired During Period, Value		(138.3)			(142.0)	(280.3)
Balances at Jan. 31, 2011	1,609.3	1,267.2		(0.6)	342.7	1,609.3
Balance (in shares) at Jan. 31, 2011	227	227,000,000
Common shares issued under stock award and stock purchase plans, Shares		8,600,000
Common shares issued under stock award and stock purchase plans, Value		176.1				176.1
Compensation expense related to stock options		108.8				108.8
Tax benefits from employee stock plans		24.3				24.3
Net income	285.3		285.3		285.3	285.3
Net loss on derivative instruments, net of taxes			10.0
Change in net unrealized gain on marketable securities, net of tax			0.2
Change in unfunded portion of pension plans			1.2
Net change in cumulative foreign currency translation loss			(4.9)
Other Comprehensive Income (Loss), Net of Tax			6.5	6.5		6.5
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			291.8
Stock Repurchased and Retired During Period, Shares	(9,700,000)	(9,700,000)
Stock Repurchased and Retired During Period, Value		(211.0)			(116.4)	(327.4)
Balances at Jan. 31, 2012	$ 1,882.9	$ 1,365.4		$ 5.9	$ 511.6	$ 1,882.9
Balance (in shares) at Jan. 31, 2012	226	225,900,000