Summary Of Business And Significant Accounting Policies (Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2012		Jan. 31, 2011		Jan. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent considerations (related to acquisitions, see Note 5)	$ 0		$ 17,138		$ 0
Cash [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	222,400		275,200
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts	0	[1]	0	[2]
Total Assets	467,450		178,319
Foreign currency derivative contracts	0	[3]	0	[4]
Contingent considerations (related to acquisitions, see Note 5)	0	[3]	0	[4]
Total Liabilities	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	26,513	[5]	26,565	[6]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Money Market Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	358,369	[5]	122,516	[6]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Corporate Notes And Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	79,358		22,706
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	3,210		6,532
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | U.S. Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Other Unobservable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts	621	[1]	1,539	[2]
Total Assets	757,943		955,566
Foreign currency derivative contracts	2,551	[3]	2,863	[4]
Contingent considerations (related to acquisitions, see Note 5)	0	[3]	0	[4]
Total Liabilities	2,551		2,863
Significant Other Unobservable Inputs (Level 2) [Member] | Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[5]	0	[6]
Significant Other Unobservable Inputs (Level 2) [Member] | Money Market Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[5]	0	[6]
Significant Other Unobservable Inputs (Level 2) [Member] | Corporate Notes And Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	504,772		707,613
Significant Other Unobservable Inputs (Level 2) [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Other Unobservable Inputs (Level 2) [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	15,426		38,886
Significant Other Unobservable Inputs (Level 2) [Member] | Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Other Unobservable Inputs (Level 2) [Member] | Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	8,789		23,081
Significant Other Unobservable Inputs (Level 2) [Member] | Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	120,495		105,039
Significant Other Unobservable Inputs (Level 2) [Member] | U.S. Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	107,840		79,408
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts	0	[1]	0	[2]
Total Assets	0		0
Foreign currency derivative contracts	0	[3]	0	[4]
Contingent considerations (related to acquisitions, see Note 5)	0	[3]	17,138	[4]
Total Liabilities	0		17,138
Significant Unobservable Inputs (Level 3) [Member] | Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[5]	0	[6]
Significant Unobservable Inputs (Level 3) [Member] | Money Market Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	[5]	0	[6]
Significant Unobservable Inputs (Level 3) [Member] | Corporate Notes And Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Significant Unobservable Inputs (Level 3) [Member] | U.S. Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Net Carrying Value - Balance [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts	621	[1]	1,539	[2]
Total Assets	1,225,393		1,133,885
Foreign currency derivative contracts	2,551	[3]	2,863	[4]
Contingent considerations (related to acquisitions, see Note 5)	0	[3]	17,138	[4]
Total Liabilities	2,551		20,001
Net Carrying Value - Balance [Member] | Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	26,513	[5]	26,565	[6]
Net Carrying Value - Balance [Member] | Money Market Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	358,369	[5]	122,516	[6]
Net Carrying Value - Balance [Member] | Corporate Notes And Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	504,772		707,613
Net Carrying Value - Balance [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	79,358		22,706
Net Carrying Value - Balance [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	15,426		38,886
Net Carrying Value - Balance [Member] | Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	3,210		6,532
Net Carrying Value - Balance [Member] | Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	8,789		23,081
Net Carrying Value - Balance [Member] | Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	120,495		105,039
Net Carrying Value - Balance [Member] | U.S. Agency Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 107,840		$ 79,408

[1] Included in "prepaid expenses and other current assets" in the accompanying Consolidated Balance Sheet as of January 31, 2012.

[2] Included in "prepaid expenses and other current assets" in the accompanying Consolidated Balance Sheet as of January 31, 2011.

[3] Included in "accrued expenses and other current liabilities" in the accompanying Consolidated Balance Sheet as of January 31, 2012.

[4] Included in "accrued expenses and other current liabilities" in the accompanying Consolidated Balance Sheet as of January 31, 2011.

[5] Included in "cash and cash equivalents" in the accompanying Consolidated Balance Sheet as of January 31, 2012, in addition to $222.4 million of cash.

[6] Included in "cash and cash equivalents" in the accompanying Consolidated Balance Sheet as of January 31, 2011, in addition to $275.2 million of cash.