SOURCES OF INCOME (Details) (USD $)	12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012	Mar. 31, 2011
Subsidiary or Equity Method Investee [Line Items]
Interest	$ 2,078,000			$ 1,980,180	$ 1,364,138
Dividends	8,093,000			6,720,441	5,432,271
Management and other income				633,616	771,738
Realized gain (loss) on investments before income tax	89,557,814			11,826,876	63,462,583
Distributed net capital gains (in dollars per share)	$ 20.34		$ 17.59
Companies more than 25% owned [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	0			0	0
Dividends	6,944,214			5,553,140	5,024,061
Management and other income	484,800			493,967	671,867
Realized gain (loss) on investments before income tax	20,861,458			(10,933,517)	70,294,097
Companies 5% to 25% owned [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	250,298			253,652	0
Dividends	868,560			1,006,572	326,940
Management and other income	66,950			59,700	13,000
Realized gain (loss) on investments before income tax	66,037,485			(45,287)	(6,863,347)
Companies less than 5% owned [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	1,756,452			1,674,051	1,304,496
Dividends	279,917			160,729	81,270
Management and other income	111,963			79,250	0
Realized gain (loss) on investments before income tax	2,658,871			22,805,680	31,833
Other sources, including temporary investment [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	71,136			52,477	59,642
Dividends	0			0	0
Management and other income	971			699	86,871
Realized gain (loss) on investments before income tax	0			0	0
Realized gain before distribution [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	2,077,886
Dividends	8,092,691
Management and other income	664,684
Realized gain (loss) on investments before income tax	89,557,814
Distribution from Realized Gain [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	0
Dividends	0
Management and other income	0
Realized gain (loss) on investments before income tax	(77,300,714)	[1]
Realized gain after distribution [Member]
Subsidiary or Equity Method Investee [Line Items]
Interest	2,077,886
Dividends	8,092,691
Management and other income	664,684
Realized gain (loss) on investments before income tax	$ 12,257,100

[1] During the twelve months ended March 31, 2013, we distributed $77,300,714 or $20.34 per share of capital gains dividends.