Employee Benefit And Retirement Plans (Narrative) (Details) (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Percent of after tax earnings contributed in profit sharing	3.00%
Recognized expenses for profit-sharing contributions	$ 293,000
Percent of employee's annual contribution	100.00%	50.00%
Percent of base earnings		4.00%
Effective maximum contribution of base earnings	4.00%	2.00%
Expense for 401(k) matching contributions	2,547,000	1,284,000	1,272,000
Accumulated other comprehensive loss	52,703,000	45,255,000
Accumulated other comprehensive loss, net of tax	32,100,000
Expected recognized net actuarial losses in net periodic pension benefit cost, before tax	1,100,000
Expected recognized net actuarial losses in net periodic pension benefit cost, after tax	700,000
Accumulated benefit obligation	149,429,000	136,264,000
Expected company contributions to pension plan in 2014	2,300,000
Company contributions to pension plans	$ 4,920,000	$ 2,871,000
Plan asset target allocation	100.00%
Capital Preservation [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	19.00%
Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	31.00%
Large Capital Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	20.00%
Large Capital Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	20.00%
Small Capital [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	6.00%
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan asset target allocation	4.00%