Income Taxes - Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Income Taxes
Unrecognized tax benefits netted against certain noncurrent deferred tax assets	$ 286,000	$ 251,000
Unrecognized tax benefits that, if recognized, would affect effective tax rate	359,000	328,000
Accrued payment of potential interest and penalties	46,000	52,000
Interest and penalties recognized	(6,000)	5,000
Gross unrecognized tax benefits
Balance at the beginning of the year	394,000	319,000	$ 281,000
Increases for tax positions taken in prior years	18,000	22,000	14,000
Decreases for tax positions taken in prior years	(8,000)		(3,000)
Increases for tax positions taken in the current year	59,000	68,000	46,000
Lapse in statute of limitations	(37,000)	(15,000)	(19,000)
Balance at the end of the year	$ 426,000	$ 394,000	$ 319,000