Cost and Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2013		Jan. 31, 2012		Jan. 31, 2011	Jan. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	$ 1,612.2		$ 1,156.9		$ 1,075.1	$ 838.7
Derivative Instruments And Hedges at Amortized Cost, Net			11.6	[1]
Unrealized Gain on Foreign Currency Derivatives, before Tax	9.2	[2]	6.5	[1]
Unrealized Loss on Foreign Currency Derivatives, before Tax	(5.9)	[2]	(2.2)	[1]
Derivative Contracts, Fair Value Disclosure	13.5	[2]	15.9	[1]
Amortized Cost Securities	2,029.2		1,327.7
Unrealized Gain on Securities	16.9		9.8
Unrealized Loss on Securities	(8.1)		(2.5)
Total	2,038.0		1,335.0
Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Trading Securities	31.1		29.8
Trading Securities, Unrealized Holding Gain	4.2		1.8
Trading Securities, Unrealized Holding Loss	0		(0.1)
Other Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis			18.3
Available-for-sale Securities, Gross Unrealized Gains			0
Available-for-sale Securities, Gross Unrealized Losses			0
Available-for-sale Securities, Fair Value Disclosure			18.3
Convertible Debt Securities, Amortized Cost	18.1	[1]
Convertible Debt Securities, Unrealized Gains	1.6	[1]
Convertible Debt Securities, Unrealized Losses	(2.2)	[1]
Convertible Debt Securities, Fair Value Disclosure	17.5	[1]
Fair Value, Inputs, Level 1
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	0	[2]	0	[1]
Total	678.3		340.6
Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	35.3		31.5
Fair Value, Inputs, Level 1 | Other Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			0
Convertible Debt Securities, Fair Value Disclosure	0	[1]
Fair Value, Inputs, Level 2
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	2.8	[2]	9.7	[1]
Total	1,327.3		965.7
Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	0		0
Fair Value, Inputs, Level 2 | Other Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			0
Convertible Debt Securities, Fair Value Disclosure	0	[1]
Fair Value, Inputs, Level 3
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	10.7	[2]	6.2	[1]
Total	32.4		28.7
Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	0		0
Fair Value, Inputs, Level 3 | Other Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			18.3
Convertible Debt Securities, Fair Value Disclosure	17.5	[1]
Commercial paper and corporate securities | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	122.9		143.7
Available-for-sale Securities, Gross Unrealized Gains	0.1		0.1
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	123.0		143.8
Commercial paper and corporate securities | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	40.4		35.3
Commercial paper and corporate securities | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	82.6		108.5
Commercial paper and corporate securities | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Certificates of deposit and time deposits | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	15.1		5.2
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	15.1		5.2
Certificates of deposit and time deposits | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	10.0		0
Certificates of deposit and time deposits | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	5.1		5.2
Certificates of deposit and time deposits | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
U.S. Treasury Securities | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	83.3		30.7
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	83.3		30.7
U.S. Treasury Securities | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	145.2		23.6
Available-for-sale Securities, Gross Unrealized Gains	0.1		0.2
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	145.3		23.8
U.S. Treasury Securities | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	83.3		30.7
U.S. Treasury Securities | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	145.3		23.8
U.S. Treasury Securities | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
U.S. Treasury Securities | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
U.S. Treasury Securities | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
U.S. Treasury Securities | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
US government agency securities | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	79.5		38.2
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	79.5		38.2
US government agency securities | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	50.8		51.4
Available-for-sale Securities, Gross Unrealized Gains	0.2		0.2
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	51.0		51.6
US government agency securities | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	79.5		38.2
US government agency securities | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	51.0		51.6
US government agency securities | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
US government agency securities | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
US government agency securities | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
US government agency securities | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Municipal securities | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	4.6		4.7
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	4.6		4.7
Municipal securities | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	36.0		4.6
Available-for-sale Securities, Gross Unrealized Gains	0.1		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	36.1		4.6
Municipal securities | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4.6		4.7
Municipal securities | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	36.1		4.6
Municipal securities | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Municipal securities | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Municipal securities | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Municipal securities | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	0.3		0.3
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	0.3		0.3
Other | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0.3		0.3
Other | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Sovereign Debt | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1.0
Available-for-sale Securities, Gross Unrealized Gains	0
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Fair Value Disclosure	1.0
Sovereign Debt | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1.0
Available-for-sale Securities, Gross Unrealized Gains	0
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Fair Value Disclosure	1.0
Sovereign Debt | Fair Value, Inputs, Level 1 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0
Sovereign Debt | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0
Sovereign Debt | Fair Value, Inputs, Level 2 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1.0
Sovereign Debt | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1.0
Sovereign Debt | Fair Value, Inputs, Level 3 | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0
Sovereign Debt | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0
Corporate debt securities | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	172.1		107.8
Available-for-sale Securities, Gross Unrealized Gains	1.4		1.0
Available-for-sale Securities, Gross Unrealized Losses	0		(0.2)
Available-for-sale Securities, Fair Value Disclosure	173.5		108.6
Corporate debt securities | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	173.5		108.6
Corporate debt securities | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Corporate debt securities | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Taxable auction rate securities | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	4.2		4.2
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value Disclosure	4.2		4.2
Taxable auction rate securities | Fair Value, Inputs, Level 1 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Taxable auction rate securities | Fair Value, Inputs, Level 2 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Taxable auction rate securities | Fair Value, Inputs, Level 3 | Marketable Securities, Noncurrent
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4.2		4.2
Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	1.8	[3]
Cash and Cash Equivalents, Fair Value Disclosure	1.8	[3]
Available-for-sale Securities, Gross Unrealized Gains	0	[3]
Available-for-sale Securities, Gross Unrealized Losses	0	[3]
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 1
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	1.8	[3]
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 3
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]
Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	392.4	[3]	493.6	[3]
Cash and Cash Equivalents, Fair Value Disclosure	392.4	[3]	493.6	[3]
Available-for-sale Securities, Gross Unrealized Gains	0	[3]	0
Available-for-sale Securities, Gross Unrealized Losses	0	[3]	0
Certificates of deposit and time deposits | Fair Value, Inputs, Level 1
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	17.2	[3]	11.3	[3]
Certificates of deposit and time deposits | Fair Value, Inputs, Level 2
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	375.2	[3]	482.3	[3]
Certificates of deposit and time deposits | Fair Value, Inputs, Level 3
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]	0
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	263.3	[3]	297.9	[3]
Cash and Cash Equivalents, Fair Value Disclosure	263.3	[3]	297.9	[3]
Available-for-sale Securities, Gross Unrealized Gains	0	[3]	0
Available-for-sale Securities, Gross Unrealized Losses	0	[3]	0
Commercial Paper | Fair Value, Inputs, Level 1
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]	0
Commercial Paper | Fair Value, Inputs, Level 2
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	263.3	[3]	297.9	[3]
Commercial Paper | Fair Value, Inputs, Level 3
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]	0
Money Market Funds
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	596.3	[3]	62.1	[3]
Cash and Cash Equivalents, Fair Value Disclosure	596.3	[3]	62.1	[3]
Available-for-sale Securities, Gross Unrealized Gains	0	[3]	0
Available-for-sale Securities, Gross Unrealized Losses	0	[3]	0
Money Market Funds | Fair Value, Inputs, Level 1
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]	0
Money Market Funds | Fair Value, Inputs, Level 2
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	596.3	[3]	62.1	[3]
Money Market Funds | Fair Value, Inputs, Level 3
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[3]	0
Rabbi Trust | Marketable Securities, Current
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	$ 35.3		$ 31.5

[1] Considered "available for sale" securities and included in "Other assets" in the accompanying Consolidated Balance Sheets.

[2] Included in “Prepaid expenses and other current assets,” "Other assets," or “Other accrued liabilities” in the accompanying Consolidated Balance Sheets.

[3] Included in “Cash and cash equivalents” in the accompanying Consolidated Balance Sheets.