CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Other Comprehensive Gain (Loss)	Total
Balance at Mar. 31, 2014	$ 9	$ 20	$ 1,578	$ 68,647	$ (37)	$ 70,217
Balance (in shares) at Mar. 31, 2014	3	20,190
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock, net
Issuance of restricted stock, net (in shares)		72
Share based compensation			1,481			1,481
Dividends declared				(13,757)		(13,757)
Excess tax benefit related to stock compensation			58			58
Net income				17,453	17,453	17,453
Other comprehensive gain (loss):
Net Change in unrealized loss on short term investments					(17)	(17)
Total comprehensive income					17,436	17,436
Balance at Mar. 31, 2015	$ 9	$ 20	3,117	72,343	(54)	75,435
Balance (in shares) at Mar. 31, 2015	3	20,262
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock, net
Issuance of restricted stock, net (in shares)		185
Share based compensation			1,612			1,612
Dividends declared				(14,615)		(14,615)
Excess tax benefit related to stock compensation			142			142
Net income				20,567	20,567	20,567
Other comprehensive gain (loss):
Net Change in unrealized loss on short term investments					54	54
Total comprehensive income					20,621	20,621
Balance at Mar. 31, 2016	$ 9	$ 20	4,871	78,295		83,195
Balance (in shares) at Mar. 31, 2016	3	20,447
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock, net		$ 1				1
Issuance of restricted stock, net (in shares)		79
Share based compensation			1,935			1,935
Dividends declared				(15,584)		(15,584)
Net income				23,819	$ 23,819	23,819
Other comprehensive gain (loss):
Total comprehensive income						23,819
Balance at Mar. 31, 2017	$ 9	$ 21	$ 6,806	$ 86,530		$ 93,366
Balance (in shares) at Mar. 31, 2017	3	20,526