Income Taxes - Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Income Taxes
Unrecognized tax benefits netted against certain noncurrent deferred tax assets	$ 580,000	$ 461,000
Unrecognized tax benefits that, if recognized, would affect effective tax rate	609,000	513,000
Accrued payment of potential interest and penalties	42,000	43,000
Interest and penalties recognized	1,000	3,000
Gross unrecognized tax benefits
Balance at the beginning of the year	586,000	426,000	$ 394,000
Increases for tax positions taken in prior years	2,000	62,000	18,000
Decreases for tax positions taken in prior years			(8,000)
Increases for tax positions taken in the current year	116,000	122,000	59,000
Lapse in statute of limitations	(17,000)	(24,000)	(37,000)
Balance at the end of the year	$ 687,000	$ 586,000	$ 426,000