Employee Retirement Benefits Employee Retirement Benefits (Details) (USD $)	12 Months Ended
Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current payroll matching percentage by the Company	4.00%
Former payroll contribution by the Company			3.00%
Contribution expense	$ 1,556,000	$ 1,254,000	$ 1,085,000
Vista Research [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current payroll matching percentage by the Company	3.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution expense	582,000	552,000	515,000
Assets held under plans	0
Assumed health care cost trend rate	8.60%	9.00%	9.51%
Impact of a one-percentage-point change in assumed health care rates to the Company's income statement	$ 1,307,000
Assumed helath care cost trend rate	5.00%

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

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