CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Operations:
Net investment income	$ 4,040	$ 4,421
Net realized gain on investments	67,521	10,079
Net increase (decrease) in unrealized appreciation of investments	(5,904)	165
Increase in net assets from operations	65,657	14,665
Distributions from:
Undistributed net investment income	(3,025)	(3,003)
Net realized gain distribution	(66,826)
Net realized gains deemed distributed to shareholders	(1,194)	(3,216)
Capital share transactions:
Allocated increase in share value for deemed distribution	1,194	3,216
Exercise of employee stock options	3,243	98
Stock option expense	334	757
Increase/(decrease) in net assets	(617)	12,517
Net assets, beginning of period	628,706	628,706
Net assets, end of period	$ 628,089	$ 551,750