Condensed Statements Of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Cash received from royalties and rents	$ 8,203,545	$ 5,986,493
Cash paid to suppliers and employees	(720,172)	(711,907)
Interest and related premium/discount received (paid)	5,014	(4,028)
NET CASH PROVIDED BY OPERATING ACTIVITIES	7,488,387	5,270,558
Cash flows from investing activities:
United States Treasury securities purchased	(1,625,000)	(1,525,000)
United States Treasury securities matured	2,600,000	1,750,000
NET CASH PROVIDED BY INVESTING ACTIVITIES	975,000	225,000
Cash flows from financing activities:
Distributions paid	(8,625,000)	(5,625,000)
NET CASH USED IN FINANCING ACTIVITIES	(8,625,000)	(5,625,000)
Net decrease in cash and cash equivalents	(161,613)	(129,442)
Cash and cash equivalents at beginning of year	750,947	668,310
CASH AND CASH EQUIVALENTS AT MARCH 31	$ 589,334	$ 538,868