Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Cash flows from operating activities:
Net earnings	$ 5,269	$ 2,847
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	2,176	1,727
Stock-based compensation expense	586	480
Bond amortization	84	146
Tax benefit of stock options exercised	104	297
Excess tax benefits from stock-based compensation	(87)	(124)
Net loss on investments	651	45
Deferred income taxes	(601)	(407)
Changes in operating assets and liabilities:
Purchases of trading securities	(9,773)	(8,385)
Proceeds from maturities and sales of trading securities	7,423	2,764
Accounts receivable, net	(1,857)	(2,311)
Prepaid expenses and other assets	(111)	415
Accounts payable and other liabilities	(469)	376
Deferred revenue	(1,369)	(878)
Net cash provided by (used in) operating activities	2,026	(3,008)
Cash flows from investing activities:
Capitalized computer software development costs	(1,265)	(1,259)
Purchases of property and equipment, net of disposals	(222)	(320)
Proceeds from maturities of investments	3,300	6,574
Net cash provided by investing activities	1,813	4,995
Cash flows from financing activities:
Repurchase of common stock		(369)
Excess tax benefits from stock based compensation	87	124
Proceeds from exercise of stock options	1,309	1,513
Dividends paid	(4,708)	(4,615)
Net cash used in financing activities	(3,312)	(3,347)
Net change in cash and cash equivalents	527	(1,360)
Cash and cash equivalents at beginning of period	23,928	21,730
Cash and cash equivalents at end of period	$ 24,455	$ 20,370