Investments in Tax-Exempt Bonds Investments of Tax-Exempt Bonds Briarwood Manor (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011 Briarwood Manor [Member]	Dec. 31, 2011 Briarwood Manor [Member]	Dec. 31, 2011 Omaha State Bank [Member]
Proceeds from Sale of Available-for-sale Securities	$ 31,872,522	$ 0	$ 0		$ 4,900,000
Undistributed Net Realized Gain (Loss) on Sale of Properties					445,000
Repayments of Long-term Debt	10,893,390	0	18,858,175			4,000,000
Available-for-sale Security, Purchase Date				Feb. 01, 2011
Available-for-sale Securities, at Par Value	$ 146,806,203	$ 145,907,502		$ 4,500,000