Condensed Statements Of Cash Flows (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Cash received from royalties and rents	$ 9,084,387	$ 15,217,173
Cash paid to suppliers and employees	(1,341,554)	(1,401,235)
Interest received	40,948	11,285
NET CASH PROVIDED BY OPERATING ACTIVITIES	7,783,781	13,827,223
Cash flows from investing activities:
U.S. Treasury securities purchased	(2,675,000)	(5,000,000)
U.S. Treasury securities matured	6,025,000	3,050,000
Expenditures for building and equipment	(7,641)
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	3,342,359	(1,950,000)
Cash flows from financing activities:
Distributions paid	(11,250,000)	(12,000,000)
NET CASH USED IN FINANCING ACTIVITIES	(11,250,000)	(12,000,000)
Net decrease in cash and cash equivalents	(123,860)	(122,777)
Cash and cash equivalents at beginning of year	643,431	750,947
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 519,571	$ 628,170