Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Mar. 31, 2018	3,000	20,601,000
Balance at Mar. 31, 2018	$ 9	$ 21	$ 9,381	$ 106,320	$ 115,731
Issuance of restricted stock, net (in shares)	0	73,000
Issuance of restricted stock, net	$ 0	$ 0	0	0	0
Share based compensation	0	0	3,097	0	3,097
Dividends declared	0	0	0	(21,888)	(21,888)
Net income	$ 0	$ 0	0	37,740	$ 37,740
Repurchased and retired shares (in shares)					0
Balance (in shares) at Mar. 31, 2019	3,000	20,674,000
Balance at Mar. 31, 2019	$ 9	$ 21	12,478	122,172	$ 134,680
Issuance of restricted stock, net (in shares)	0	105,000
Issuance of restricted stock, net	$ 0	$ 0	0	0	0
Share based compensation	0	0	2,822	0	2,822
Dividends declared	0	0	0	(21,846)	(21,846)
Net income	$ 0	$ 0	0	25,851	$ 25,851
Repurchased and retired shares (in shares)	0	(613,000)			(613,000)
Repurchased and retired shares	$ 0	$ (1)	(11,496)	0	$ (11,497)
Balance (in shares) at Mar. 31, 2020	3,000	20,166,000
Balance at Mar. 31, 2020	$ 9	$ 20	3,804	126,177	130,010
Issuance of restricted stock, net (in shares)	0	103,000
Issuance of restricted stock, net	$ 0	$ 0	0	0	0
Share based compensation	0	0	3,307	0	3,307
Dividends declared	0	0	0	(22,639)	(22,639)
Net income	$ 0	$ 0	0	30,603	$ 30,603
Repurchased and retired shares (in shares)					0
Balance (in shares) at Mar. 31, 2021	3,000	20,269,000
Balance at Mar. 31, 2021	$ 9	$ 20	$ 7,111	$ 134,141	$ 141,281