Financial Instruments Cost and Fair Value of Financial Instuments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Apr. 30, 2013		Jan. 31, 2013		Apr. 30, 2012	Jan. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 1,655.8		$ 1,612.2		$ 1,074.5	$ 1,156.9
Derivative Instruments and Hedges, Carrying Amount	11.0	[1]	10.2	[1]
Unrealized Gain on Foreign Currency Derivatives, before Tax	9.9	[1]	9.2	[1]
Unrealized Loss on Foreign Currency Derivatives, before Tax	3.4	[1]	5.9	[1]
Derivative Contracts, Fair Value Disclosure	17.5	[1]	13.5	[1]
Amortized Cost Securities	1,868.2		2,029.2
Unrealized Gain on Securities	19.6		16.9
Unrealized Loss on Securities	(6.3)		(8.1)
Fair Value, Assets Measured on Recurring Basis	1,881.5		2,038.0
Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value			1.8	[2]
Available-for-sale Securities, Gross Unrealized Gains			0	[2]
Available-for-sale Securities, Gross Unrealized Losses			0	[2]
Cash and Cash Equivalents, Fair Value Disclosure			1.8	[2]
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	270.1	[2]	263.3	[2]
Available-for-sale Securities, Gross Unrealized Gains	0	[2]	0	[2]
Available-for-sale Securities, Gross Unrealized Losses	0	[2]	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	270.1	[2]	263.3	[2]
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	428.2	[2]	596.3	[2]
Available-for-sale Securities, Gross Unrealized Gains	0	[2]	0	[2]
Available-for-sale Securities, Gross Unrealized Losses	0	[2]	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	428.2	[2]	596.3	[2]
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	7.4	[2]
Available-for-sale Securities, Gross Unrealized Gains	0	[2]
Available-for-sale Securities, Gross Unrealized Losses	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	7.4	[2]
Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	313.6	[2]	392.4	[2]
Available-for-sale Securities, Gross Unrealized Gains	0	[2]	0	[2]
Available-for-sale Securities, Gross Unrealized Losses	0	[2]	0	[2]
Cash and Cash Equivalents, Fair Value Disclosure	313.6	[2]	392.4	[2]
Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	0	[1]	0	[1]
Fair Value, Assets Measured on Recurring Basis	698.0		678.3
Level 1 [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure			1.8	[2]
Level 1 [Member] | Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]	0	[2]
Level 1 [Member] | Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]	0	[2]
Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	7.4	[2]
Level 1 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	32.2	[2]	17.2	[2]
Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	8.0	[1]	2.8	[1]
Fair Value, Assets Measured on Recurring Basis	1,153.4		1,327.3
Level 2 [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure			0	[2]
Level 2 [Member] | Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	270.1	[2]	263.3	[2]
Level 2 [Member] | Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	428.2	[2]	596.3	[2]
Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]
Level 2 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	281.4	[2]	375.2	[2]
Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Derivative Contracts, Fair Value Disclosure	9.5	[1]	10.7	[1]
Fair Value, Assets Measured on Recurring Basis	30.1		32.4
Level 3 [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure			0	[2]
Level 3 [Member] | Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]	0	[2]
Level 3 [Member] | Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]	0	[2]
Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]
Level 3 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]	0	[2]
Other Long-term Investments [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0.2		0.1
Available-for-sale Securities, Gross Unrealized Losses			0
Available-for-sale Securities, Amortized Cost Basis	120.1		145.2
Available-for-sale Securities, Fair Value Disclosure	120.3		145.3
Other Long-term Investments [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0.2		0.2
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	45.5		50.8
Available-for-sale Securities, Fair Value Disclosure	45.7		51.0
Other Long-term Investments [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0.3		0.1
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	44.5		36.0
Available-for-sale Securities, Fair Value Disclosure	44.8		36.1
Other Long-term Investments [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	1.0		1.0
Available-for-sale Securities, Fair Value Disclosure	1.0		1.0
Other Long-term Investments [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	1.4		1.4
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	178.8		172.1
Available-for-sale Securities, Fair Value Disclosure	180.2		173.5
Other Long-term Investments [Member] | Taxable Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains			0
Available-for-sale Securities, Gross Unrealized Losses			0
Available-for-sale Securities, Amortized Cost Basis			4.2
Available-for-sale Securities, Fair Value Disclosure			4.2
Other Long-term Investments [Member] | Level 1 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	120.3		145.3
Other Long-term Investments [Member] | Level 1 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	45.7		51.0
Other Long-term Investments [Member] | Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	44.8		36.1
Other Long-term Investments [Member] | Level 1 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 1 [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	180.2		173.5
Other Long-term Investments [Member] | Level 1 [Member] | Taxable Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			0
Other Long-term Investments [Member] | Level 2 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 2 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 2 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1.0		1.0
Other Long-term Investments [Member] | Level 2 [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 2 [Member] | Taxable Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			0
Other Long-term Investments [Member] | Level 3 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 3 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 3 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 3 [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Long-term Investments [Member] | Level 3 [Member] | Taxable Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			4.2
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Trading Securities	33.3		31.1
Trading Securities, Unrealized Holding Gain	5.1		4.2
Trading Securities, Unrealized Holding Loss	0		0
Trading Securities, Fair Value Disclosure	38.4		35.3
Short-term Investments [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains			0.1
Available-for-sale Securities, Gross Unrealized Losses			0
Available-for-sale Securities, Amortized Cost Basis			122.9
Available-for-sale Securities, Fair Value Disclosure			123.0
Short-term Investments [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	14.9		15.1
Available-for-sale Securities, Fair Value Disclosure	14.9		15.1
Short-term Investments [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0.1
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Amortized Cost Basis	210.5
Available-for-sale Securities, Fair Value Disclosure	210.6
Short-term Investments [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	71.2		83.3
Available-for-sale Securities, Fair Value Disclosure	71.2		83.3
Short-term Investments [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	73.9		79.5
Available-for-sale Securities, Fair Value Disclosure	73.9		79.5
Short-term Investments [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	21.8		4.6
Available-for-sale Securities, Fair Value Disclosure	21.8		4.6
Short-term Investments [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	1.0		1.0
Available-for-sale Securities, Fair Value Disclosure	1.0		1.0
Short-term Investments [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Amortized Cost Basis	0.3		0.3
Available-for-sale Securities, Fair Value Disclosure	0.3		0.3
Short-term Investments [Member] | Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	38.4		35.3
Short-term Investments [Member] | Level 1 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			40.4
Short-term Investments [Member] | Level 1 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4.9		10.0
Short-term Investments [Member] | Level 1 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	56.9
Short-term Investments [Member] | Level 1 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	71.2		83.3
Short-term Investments [Member] | Level 1 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	73.9		79.5
Short-term Investments [Member] | Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	21.8		4.6
Short-term Investments [Member] | Level 1 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 1 [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0.3		0.3
Short-term Investments [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 2 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			82.6
Short-term Investments [Member] | Level 2 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	10.0		5.1
Short-term Investments [Member] | Level 2 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	153.7
Short-term Investments [Member] | Level 2 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 2 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 2 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1.0		1.0
Short-term Investments [Member] | Level 2 [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Trading Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure			0
Short-term Investments [Member] | Level 3 [Member] | Bank Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | Commercial paper and corporate securities [member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0
Short-term Investments [Member] | Level 3 [Member] | US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | Sovereign Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Short-term Investments [Member] | Level 3 [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Other Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Convertible Debt Securities, Amortized Cost	21.1	[3]	18.1	[3]
Convertible Debt Securities, Unrealized Gains	2.4	[3]	1.6	[3]
Convertible Debt Securities, Unrealized Losses	2.9	[3]	2.2	[3]
Convertible Debt Securities, Fair Value Disclosure	20.6	[3]	17.5	[3]
Other Assets [Member] | Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Convertible Debt Securities, Fair Value Disclosure	0	[3]	0	[3]
Other Assets [Member] | Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Convertible Debt Securities, Fair Value Disclosure	0	[3]	0	[3]
Other Assets [Member] | Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Convertible Debt Securities, Fair Value Disclosure	$ 20.6	[3]	$ 17.5	[3]

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

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

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