Notes Payable and Accrued Interest (Details) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Notes payable and accrued interest [Abstract]
Credit Facility principal	$ 82,800,000	$ 65,200,000
Credit Facility accrued interest	125,000	472,700
Notes payable and accrued interest	82,925,000	65,672,700
Warrant [Member]
Class of Warrant or Right [Line Items]
Maximum number of shares called through warrant (in shares)	81,224
Class of warrant or right exercise price (in dollars per share)	$ 8.75
Credit Facility [Member]
Notes payable and accrued interest [Abstract]
Credit facility maximum borrowing capacity	90,000,000	90,000,000
Expiration date of credit facility	Apr. 29, 2013
Unused amount of the credit facility	7,200,000	24,800,000
Available borrowing capacity	$ 8,887,900	$ 17,388,300
Weighted average interest rate on credit facility (in hundredths)	4.00%	4.17%