CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net (loss) income	$ (21,184)	$ 79,287	$ 57,526	$ 178,580
Change in net unrealized holding gain (loss) on available-for-sale securities	2,586	(5,881)	2,448	(3,953)
Change in net foreign currency translation adjustment	1,140	0	1,140	0
Other comprehensive income (loss)	3,726	(5,881)	3,588	(3,953)
Total comprehensive (loss) income	$ (17,458)	$ 73,406	$ 61,114	$ 174,627