Financial Instruments Cost and Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2014		Jan. 31, 2014		Jul. 31, 2013	Jan. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	$ 1,323.1		$ 1,853.0		$ 1,401.0	$ 1,612.2
Derivative contracts, Amortized Cost	6.7	[1]	10.8	[1]
Derivative contracts, Gross unrealized gains	7.1	[1]	14.8	[1]
Derivative contracts, Gross unrealized losses	(4.8)	[1]	(6.0)	[1]
Derivative contracts, Fair Value	9.0	[1]	19.6	[1]
Amortized Cost	1,385.1		1,545.3
Gross unrealized gains	17.3		22.4
Gross unrealized losses	(11.4)		(10.5)
Fair Value	1,391.0		1,557.2
Short-term available for sale
Schedule of Available-for-sale Securities [Line Items]
Mutual funds, Amortized Cost	37.7		35.6
Mutual funds, Gross unrealized gains	5.2		3.3
Mutual funds, Gross unrealized losses	0		0
Mutual funds, Fair Value	42.9		38.9
Short-term available for sale | Commercial paper and corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	382.1		261.0
Marketable securities, Gross unrealized gains	0		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	382.1		261.0
Short-term available for sale | Time deposits
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	116.6		37.1
Marketable securities, Gross unrealized gains	0		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	116.6		37.1
Short-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	6.0		42.7
Marketable securities, Gross unrealized gains	0		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	6.0		42.7
Short-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	6.2		11.3
Marketable securities, Gross unrealized gains	0		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	6.2		11.3
Short-term available for sale | U.S. treasury bills
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	6.0
Marketable securities, Gross unrealized gains	0
Marketable securities, Gross unrealized losses	0
Marketable securities, Fair Value	6.0
Short-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	13.7		11.7
Marketable securities, Gross unrealized gains	0.1		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	13.8		11.7
Short-term available for sale | Other
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	9.7	[2]	11.4	[3]
Marketable securities, Gross unrealized gains	0	[2]	0	[3]
Marketable securities, Gross unrealized losses	0	[2]	0	[3]
Marketable securities, Fair Value	9.7	[2]	11.4	[3]
Long-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	40.7		43.3
Marketable securities, Gross unrealized gains	0		0.1
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	40.7		43.4
Long-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	6.3		9.8
Marketable securities, Gross unrealized gains	0		0
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	6.3		9.8
Long-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	28.8		43.5
Marketable securities, Gross unrealized gains	0.1		0.3
Marketable securities, Gross unrealized losses	0		0
Marketable securities, Fair Value	28.9		43.8
Long-term available for sale | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Amortized Cost	186.1		179.7
Marketable securities, Gross unrealized gains	0.3		0.7
Marketable securities, Gross unrealized losses	(0.2)		(0.1)
Marketable securities, Fair Value	186.2		180.3
Convertible debt securities
Schedule of Available-for-sale Securities [Line Items]
Convertible debt securities, Amortized Cost	16.1	[4]	21.4	[4]
Convertible debt securities, Gross unrealized gains	4.5	[4]	3.2	[4]
Convertible debt securities, Gross unrealized losses	(6.4)	[4]	(4.4)	[4]
Convertible debt securities, Fair Value	14.2	[4]	20.2	[4]
Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	202.3	[5]	280.7	[5]
Cash equivalents, Fair Value	202.3	[5]	280.7	[5]
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	226.8	[5]	280.5	[5]
Cash equivalents, Fair Value	226.8	[5]	280.5	[5]
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	2.0	[5]	2.0	[5]
Cash equivalents, Fair Value	2.0	[5]	2.0	[5]
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	91.3	[5]	262.8	[5]
Cash equivalents, Fair Value	91.3	[5]	262.8	[5]
Level 1
Schedule of Available-for-sale Securities [Line Items]
Derivative contracts, Fair Value	0	[1]	0	[1]
Fair Value	478.7		521.1
Level 1 | Short-term available for sale
Schedule of Available-for-sale Securities [Line Items]
Mutual funds, Fair Value	42.9		38.9
Level 1 | Short-term available for sale | Commercial paper and corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	115.3		95.4
Level 1 | Short-term available for sale | Time deposits
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 1 | Short-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	6.0		42.7
Level 1 | Short-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	6.2		11.3
Level 1 | Short-term available for sale | U.S. treasury bills
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	6.0
Level 1 | Short-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	13.8		11.7
Level 1 | Short-term available for sale | Other
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	9.7	[2]	11.4	[3]
Level 1 | Long-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	40.7		43.4
Level 1 | Long-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	6.3		9.8
Level 1 | Long-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	28.9		43.8
Level 1 | Long-term available for sale | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	186.2		180.3
Level 1 | Convertible debt securities
Schedule of Available-for-sale Securities [Line Items]
Convertible debt securities, Fair Value	0	[4]	0	[4]
Level 1 | Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	14.7	[5]	30.4	[5]
Level 1 | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 1 | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	2.0	[5]	2.0	[5]
Level 1 | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 2
Schedule of Available-for-sale Securities [Line Items]
Derivative contracts, Fair Value	4.9	[1]	10.5	[1]
Fair Value	894.0		1,006.8
Level 2 | Short-term available for sale
Schedule of Available-for-sale Securities [Line Items]
Mutual funds, Fair Value	0		0
Level 2 | Short-term available for sale | Commercial paper and corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	266.8		165.6
Level 2 | Short-term available for sale | Time deposits
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	116.6		37.1
Level 2 | Short-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Short-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Short-term available for sale | U.S. treasury bills
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0
Level 2 | Short-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Short-term available for sale | Other
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0	[2]	0	[3]
Level 2 | Long-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Long-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Long-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Long-term available for sale | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 2 | Convertible debt securities
Schedule of Available-for-sale Securities [Line Items]
Convertible debt securities, Fair Value	0	[4]	0	[4]
Level 2 | Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	187.6	[5]	250.3	[5]
Level 2 | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	226.8	[5]	280.5	[5]
Level 2 | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 2 | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	91.3	[5]	262.8	[5]
Level 3
Schedule of Available-for-sale Securities [Line Items]
Derivative contracts, Fair Value	4.1	[1]	9.1	[1]
Fair Value	18.3		29.3
Level 3 | Short-term available for sale
Schedule of Available-for-sale Securities [Line Items]
Mutual funds, Fair Value	0		0
Level 3 | Short-term available for sale | Commercial paper and corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Short-term available for sale | Time deposits
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Short-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Short-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Short-term available for sale | U.S. treasury bills
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0
Level 3 | Short-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Short-term available for sale | Other
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0	[2]	0	[3]
Level 3 | Long-term available for sale | Agency bond
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Long-term available for sale | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Long-term available for sale | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Long-term available for sale | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities, Fair Value	0		0
Level 3 | Convertible debt securities
Schedule of Available-for-sale Securities [Line Items]
Convertible debt securities, Fair Value	14.2	[4]	20.2	[4]
Level 3 | Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 3 | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 3 | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	0	[5]	0	[5]
Level 3 | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents, Fair Value	$ 0	[5]	$ 0	[5]

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

[2] Consists of agency discount notes, certificates of deposit, and other short-term securities.

[3] Consists of agency discount notes, U.S. treasury bills, and other short-term securities.

[4] Considered “available for sale” and included in “Other assets” in the accompanying Condensed Consolidated Balance Sheets.

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