Fair Value Measurements (Schedule Of Financial Instruments) (Details) (USD $)	Oct. 31, 2011		Jan. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 827,000		$ 957,000
Contingent consideration asset recorded for sale of business	780,000		722,000
Financial assets	211,801,000		269,909,000
Derivative liabilities	1,426,000		1,926,000
Contingent consideration liability for business combination	34,623,000		3,686,000
Financial liabilities	36,049,000		5,612,000
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	9,382,000	[1]	9,375,000	[1]
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	150,553,000	[1]	186,414,000	[1]
Auction Rate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	50,259,000		72,441,000
Commercial Paper And Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	145,900,000		162,400,000
Restricted cash and bank deposits	14,100,000		33,400,000
Quoted Prices To Active Markets For Identical Instruments (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	150,553,000		186,414,000
Quoted Prices To Active Markets For Identical Instruments (Level 1) [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	150,553,000	[1]	186,414,000	[1]
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	827,000		957,000
Financial assets	10,209,000		10,332,000
Derivative liabilities	1,426,000		1,926,000
Financial liabilities	1,426,000		1,926,000
Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	9,382,000	[1]	9,375,000	[1]
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration asset recorded for sale of business	780,000		722,000
Financial assets	51,039,000		73,163,000
Contingent consideration liability for business combination	34,623,000		3,686,000
Financial liabilities	34,623,000		3,686,000
Significant Unobservable Inputs (Level 3) [Member] | Auction Rate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 50,259,000		$ 72,441,000

[1] As of October 31, 2011, $145.9 million of commercial paper and money market funds were classified in "Cash and cash equivalents" and $14.1 million of money market funds were classified in "Restricted cash and bank deposits" within the condensed consolidated balance sheets. As of January 31, 2011, $162.4 million of commercial paper and money market funds were classified in "Cash and cash equivalents" and $33.4 million of money market funds were classified in "Restricted cash and bank time deposits" within the condensed consolidated balance sheets.