Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Note 20 - Revision of Previously Issued Consolidated Financial Statements - Summary of Significant Revisions (Details) - USD ($)	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2020	Apr. 30, 2020	Dec. 31, 2019	Apr. 30, 2019	May 01, 2018	Apr. 30, 2018
Securities available-for-sale
Equity securities	$ 23,582,000	14,125,000	$ 14,125,000	10,622,000
Available-for-sale Fixed Income securities	2,600,000	15,079,000	15,079,000	11,206,000
Retained earnings	72,502,000	57,374,000	57,374,000	50,242,000
Accumulated other comprehensive income, net of tax	3,000	131,000	131,000	34,000
Total shareholders' equity	67,013,000	53,539,000	53,539,000	47,524,000	$ 47,524,000		$ 43,541,000
Investment gains/(losses)	5,420,000	(789,000)	(789,000)	1,591,000	1,591,000
Income before income taxes	30,276,000	20,651,000	20,651,000	16,313,000	16,313,000
Income tax provision	6,996,000	5,708,000	5,708,000	4,304,000	4,304,000
Net income	$ 23,280,000	$ 14,943,000	$ 14,943,000	$ 12,009,000	$ 12,009,000
Earnings per share, basic & fully diluted (in dollars per share)	$ 2.43	$ 1.55	$ 1.55	$ 1.24	$ 1.24
Change in unrealized gains on Fixed Income securities, net of taxes	$ (128,000)	$ 97,000	$ 97,000	$ 36,000	$ 36,000
Other comprehensive income/(loss)	(128,000)	97,000	97,000	36,000	36,000
Comprehensive income	23,152,000	15,040,000	15,040,000	12,045,000	12,045,000
Investment (gains)/losses	4,710,000	1,414,000	(1,414,000)	(1,087,000)	1,087,000
Deferred income taxes	543,000	154,000	154,000	740,000	740,000
Total adjustments	(6,870,000)	(1,198,000)	(1,198,000)	(515,000)	(515,000)
Net cash provided by operating activities	$ 16,410,000	13,745,000	$ 13,745,000	11,494,000	$ 11,494,000
Cumulative Effect, Period of Adoption, Adjustment [Member]
Total shareholders' equity
Accounting Standards Update 2016-01 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Total shareholders' equity						$ 0
Previously Reported [Member]
Securities available-for-sale		29,204,000		21,828,000
Equity securities
Available-for-sale Fixed Income securities
Retained earnings		56,450,000		48,598,000
Accumulated other comprehensive income, net of tax		1,055,000		1,678,000
Total shareholders' equity		53,539,000		47,524,000
Investment gains/(losses)		44,000		504,000
Income before income taxes		21,484,000		15,226,000
Income tax provision		5,821,000		4,076,000
Net income		$ 15,663,000		$ 11,150,000
Earnings per share, basic & fully diluted (in dollars per share)		$ 1.62		$ 1.15
Change in unrealized gains on Fixed Income securities, net of taxes		$ (623,000)		$ 895,000
Other comprehensive income/(loss)		(623,000)		895,000
Comprehensive income		15,040,000		12,045,000
Investment (gains)/losses		581,000
Deferred income taxes		267,000		512,000
Total adjustments		(1,918,000)		344,000
Net cash provided by operating activities		13,745,000		11,494,000
Previously Reported [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Total shareholders' equity
Revision of Prior Period, Accounting Standards Update, Adjustment [Member] \| Accounting Standards Update 2016-01 [Member]
Securities available-for-sale		(29,204,000)		(21,828,000)
Equity securities		14,125,000		10,622,000
Available-for-sale Fixed Income securities		15,079,000		11,206,000
Retained earnings		924,000		1,644,000
Accumulated other comprehensive income, net of tax		(924,000)		(1,644,000)
Total shareholders' equity
Investment gains/(losses)		(833,000)		1,087,000
Income before income taxes		(833,000)		1,087,000
Income tax provision		(113,000)		228,000
Net income		$ (720,000)		$ 859,000
Earnings per share, basic & fully diluted (in dollars per share)		$ (0.07)		$ 0.09
Change in unrealized gains on Fixed Income securities, net of taxes		$ 720,000		$ (859,000)
Other comprehensive income/(loss)		720,000		(859,000)
Comprehensive income
Investment (gains)/losses		833,000		(1,087,000)
Deferred income taxes		(113,000)		228,000
Total adjustments		720,000		(859,000)
Net cash provided by operating activities
Revision of Prior Period, Accounting Standards Update, Adjustment [Member] \| Accounting Standards Update 2016-01 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Total shareholders' equity