Condensed Statements Of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Cash received from royalties and rents	$ 17,964,950	$ 12,288,951
Cash paid to suppliers and employees	(2,386,888)	(2,274,943)
Interest received	13,749	69,306
NET CASH PROVIDED BY OPERATING ACTIVITIES	15,591,811	10,083,314
Cash flows from investing activities:
U.S. Treasury securities purchased	(6,075,000)	(2,450,000)
U.S. Treasury securities matured	4,275,000	3,250,000
Expenditures for building and equipment	(18,685)	(22,486)
NET CASH (USED IN) PROVIDED BY INVESTING ACTIVITIES	(1,818,685)	777,514
Cash flows from financing activities:
Distributions paid	(13,500,000)	(11,025,000)
NET CASH USED IN FINANCING ACTIVITIES	(13,500,000)	(11,025,000)
Net increase (decrease) in cash and cash equivalents	273,126	(164,172)
Cash and cash equivalents at beginning of year	668,310	924,234
CASH AND CASH EQUIVALENTS AT SEPTEMBER 30	$ 941,436	$ 760,062