CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net income	$ 6,601	$ 11,432	$ 12,931	$ 18,322
Other comprehensive income (loss):
Net change in unrealized gain (loss) on investments	(15)	(5)	(32)	10
Tax provision (benefit) on other comprehensive income (loss)	(5)	(2)	(12)	4
Other comprehensive income (loss), net of tax	(10)	(3)	(20)	6
Comprehensive income	$ 6,591	$ 11,429	$ 12,911	$ 18,328