Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Mar. 31, 2012
Comprehensive Income [Abstract]
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	$ 5,549		$ 5,549		$ 3,101
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	1,140		1,140		0
Accumulated Other Comprehensive Income (Loss), Net of Tax	6,689		6,689		3,101
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	2,586	(5,881)	2,448	(3,953)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	1,140	0	1,140	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 3,726	$ (5,881)	$ 3,588	$ (3,953)