CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net income	$ 3,996	$ 12,909	$ 7,225	$ 15,773
Other comprehensive income (loss):
Net change in unrealized gain (loss) on investments	8	44	(14)	38
Provision (benefit) for income taxes related to items of other comprehensive income	3	18	(6)	16
Other comprehensive income (loss), net of tax	5	26	(8)	22
Comprehensive income	$ 4,001	$ 12,935	$ 7,217	$ 15,795