Investments and Dispositions (Details) (USD $)	3 Months Ended		9 Months Ended				0 Months Ended		0 Months Ended	9 Months Ended	0 Months Ended	9 Months Ended								9 Months Ended		0 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Atlantic-EPR I [Member]	Sep. 30, 2012 First Mortgage [Member]	Feb. 23, 2012 TopGolf [Member] properties	Sep. 21, 2012 TopGolf [Member]	Feb. 28, 2012 Jacksonville and Indianapolis [Member] properties	Sep. 30, 2012 Jacksonville and Indianapolis [Member]	Jun. 14, 2012 Frank Theatres Southern Pines [Member] properties	Sep. 30, 2012 Public Charter School Property Member properties	Sep. 30, 2012 Highmark School Development Member properties	Sep. 30, 2012 Portfolio Charter Investments [Member] properties	Sep. 30, 2012 entertainment properties [Member] properties	Sep. 30, 2012 Theatre Properties [Member] properties	Sep. 30, 2012 redevelopment project [Domain] properties	Sep. 30, 2012 Highmark Member	Jul. 31, 2012 Highmark Member	Sep. 30, 2012 entertainmentpropertiescompleted [Member]	Sep. 30, 2012 Concord Resort [Member]	Feb. 29, 2012 Basis School, Inc. [Member] First Mortgage [Member] sqft	Sep. 30, 2012 Basis School, Inc. [Member] First Mortgage [Member]	Sep. 30, 2012 Montparnasse56 [Member] First Mortgage [Member]	Jun. 28, 2012 Montparnasse56 [Member] First Mortgage [Member]	Sep. 30, 2012 UMEPrep [Member] First Mortgage [Member] acre	Sep. 26, 2012 UMEPrep [Member] First Mortgage [Member]	Sep. 30, 2012 Ski Resorts [Member] mortgagenotes properties	Sep. 30, 2012 ski resorts-new hampshire [Member]	Jun. 30, 2012 Buena Vista Winery & Vineyards [Member] acre	Sep. 30, 2012 Buena Vista Winery & Vineyards [Member]
Schedule of Equity Method Investments [Line Items]
Conversion of equity to mortgage loan related to atlantic-EPR I			$ 14,852,000	$ 0	$ 14,900,000
Mortgage Loans on Real Estate, Interest Rate						9.50%																9.00%		10.65%		10.25%
mortgage loan on real estate, interest rate, increase																						0.50%				0.50%
Frequency of Interest Rate Increases (In Years)																						4 years				5 years
mortgage loans on real estate, effective interest rate																						9.30%				10.30%
mortgage loans on real estate, servicer fee																						2.00%				2.00%
Number of properties acquired (in properties)							2		2		1
Business acquisition purchase price							20,000,000	7,300,000	13,700,000		6,500,000
Commitment to fund project development								4,700,000	11,500,000						73,800,000				5,400,000
Amount funded for construction costs										7,800,000		46,900,000			6,000,000			3,600,000		13,400,000
amount funded for expansion costs												5,600,000
number of properties, completion of expansion												2
number of development properties															11	7	4
Secured first mortgage loan agreement																						19,300,000			36,000,000		3,400,000
number of acres																										28
Approximate square footage of property (in square feet)																						40,000
Carrying amount of mortgage note					16,300,000																		18,500,000	36,000,000		1,000,000		42,600,000
number of properties, completion of development												5	3	2	4
Number Of Acres Sold																														197
Interest Receivable																								32,000
Proceeds from Sale of Property, Plant, and Equipment																															13,000,000
Gain on sale or acquisition of real estate	0	16,000	720,000	18,309,000																											0
Advanced under secure mortgage loan agreement					4,000,000																							8,900,000	4,600,000
Mortgage Loans on Real Estate, Number of Loans																												2
Number of Properties Securing Mortgage Note																												3
Payments to Acquire Productive Assets			$ 42,094,000	$ 46,427,000																	$ 7,000,000