Investments and Financial Instruments Measured at Fair Value on a Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions	Apr. 30, 2011		Jan. 31, 2011
Assets
Foreign currency derivative contracts	$ 4.7	[1]	$ 5.1	[1]
Total	1,261.3		1,155.0
Liabilities
Foreign currency derivative contracts	4.6	[2]	1.2	[2]
Total	4.6		1.2
Commercial paper and corporate securities
Assets
Marketable securities	250.8		201.6
Commercial paper and corporate securities | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Marketable securities	250.8		191.6
Commercial paper and corporate securities | Significant Other Observable Inputs (Level 2)
Assets
Marketable securities			10.0
Mutual Funds
Assets
Marketable securities	34.5		31.3
Mutual Funds | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Marketable securities	34.5		31.3
Taxable auction rate securities
Assets
Marketable securities	4.2		4.2
Taxable auction rate securities | Significant Unobservable Inputs (Level 3)
Assets
Marketable securities	4.2		4.2
Certificates of deposit and time deposits
Assets
Cash equivalents	487.4	[3]	383.3	[3]
Marketable securities	24.2		29.0
Certificates of deposit and time deposits | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Cash equivalents	0.3	[3]	97.9	[3]
Marketable securities			25.0
Certificates of deposit and time deposits | Significant Other Observable Inputs (Level 2)
Assets
Cash equivalents	487.1	[3]	285.4	[3]
Marketable securities	24.2		4.0
US government agency securities
Assets
Marketable securities	62.8		60.1
US government agency securities | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Marketable securities	62.8		60.1
Sovereign Debt
Assets
Marketable securities	5.0		13.1
Sovereign Debt | Significant Other Observable Inputs (Level 2)
Assets
Marketable securities	5.0		13.1
Municipal securities
Assets
Marketable securities	13.1		13.4
Municipal securities | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Marketable securities	13.1		13.4
Other
Assets
Marketable securities	0.3		0.3
Other | Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Marketable securities	0.3		0.3
Convertible Debt Securities
Assets
Convertible debt securities	14.5	[4]
Convertible Debt Securities | Significant Unobservable Inputs (Level 3)
Assets
Convertible debt securities	14.5	[4]
Quoted Prices in Active Markets for Identical Assets ( Level 1)
Assets
Total	401.2		458.4
Quoted Prices in Active Markets for Identical Assets ( Level 1) | U.S. Treasury Securities
Assets
Marketable securities	39.4		38.8
Significant Other Observable Inputs (Level 2)
Assets
Foreign currency derivative contracts	4.7	[1]	5.1	[1]
Total	841.4		692.4
Liabilities
Foreign currency derivative contracts	4.6	[2]	1.2	[2]
Total	4.6		1.2
Significant Other Observable Inputs (Level 2) | Commercial Paper
Assets
Cash equivalents	246.4	[3]	331.0	[3]
Significant Other Observable Inputs (Level 2) | Money market funds
Assets
Cash equivalents	74.0	[3]	43.8	[3]
Significant Unobservable Inputs (Level 3)
Assets
Total	18.7		4.2
Commercial Paper
Assets
Cash equivalents	246.4	[3]	331.0	[3]
Money market funds
Assets
Cash equivalents	74.0	[3]	43.8	[3]
U.S. Treasury Securities
Assets
Marketable securities	$ 39.4		$ 38.8

[1] Included in "Prepaid expenses and other current assets" in the accompanying Condensed Consolidated Balance Sheets.

[2] Included in "Other accrued liabilities" in the accompanying Condensed Consolidated Balance Sheets.

[3] Included in "Cash and cash equivalents" in the accompanying Condensed Consolidated Balance Sheets.

[4] Included in "Other assets" in the accompanying Condensed Consolidated Balance Sheets.