Income Taxes Narratives (Details) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010	Jan. 31, 2009
Income Tax Contingency [Line Items]
Income tax holiday by Israeli government for approved enterprises (in years)	2 years
Unrecognized tax withholdings on premanently reinvested earnings	$ 255,900,000	$ 154,700,000	$ 207,400,000
Earnings from certain subsidiairies not considered permanently reinvested	170,300,000
Domestic and foreign tax credit carryforwards	75,100,000	42,200,000
Gross unrecognized tax benefits	403,884,000	389,799,000	370,034,000	365,549,000
Unrecognized tax benefits, if recognized would impact effective tax rate	132,900,000	109,900,000
Accrued interest and penalties	54,800,000	54,900,000
Estimate of decrease in unrecognized tax benefits from lapse of statutes of limitations and settlements	8,500,000
Minimum [Member]
Income Tax Contingency [Line Items]
Period of reduced income tax rate (in years)	5
Maximum [Member]
Income Tax Contingency [Line Items]
Period of reduced income tax rate (in years)	15
Israel [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Reduced Income Tax Rate	10.00%
Israel [Member] | Maximum [Member]
Income Tax Contingency [Line Items]
Reduced Income Tax Rate	15.00%
Foreign Country [Member]
Income Tax Contingency [Line Items]
Finite loss carryforward for net operaing losses	9,300,000
Permanent Establishment [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits relating to lapse of statutes of limitations and settlements	2,200,000
Events Related to Majority-Owned Subsidiaries [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits relating to lapse of statutes of limitations and settlements	4,000,000
Other Tax Positions [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits relating to lapse of statutes of limitations and settlements	$ 2,300,000