Income Taxes Difference of Effective Tax Rate from Federal Tax Rate (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Disclosure Difference of Effective Tax Rate From Federal Tax Rate [Abstract]
Federal tax, at statutory rate	$ 58,725	$ 57,074	$ 49,467
State tax, net of federal benefit	900	355	(65)
Impact of international operations including withholding taxes and other reserves	(27,042)	(46,632)	(50,275)
Repatriation of foreign subsidiary earnings	21,969	20,367	12,661
Foreign tax credits	(5,143)	(5,489)	(8,203)
Tax credits (excluding foreign tax credits)	(8,089)	(12,571)	(11,782)
Amortization of deferred charge	1,168	(2,311)	0
Losses and tax credits for which no benefit has been realized	(26,443)	(5,929)	5,978
Stock-based compensation expense	2,929	2,593	1,895
Non-deductible meals and entertainment	1,238	1,087	1,021
Other, net	2,369	966	2,004
Provision (benefit) for income taxes	$ 22,581us-gaap_IncomeTaxExpenseBenefit	$ 9,510us-gaap_IncomeTaxExpenseBenefit	$ 2,701us-gaap_IncomeTaxExpenseBenefit

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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