Investments and Dispositions (Details) (USD $)	3 Months Ended				0 Months Ended		3 Months Ended	0 Months Ended		3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Atlantic-EPR I [Member]	Mar. 31, 2012 First Mortgage [Member]	Feb. 23, 2012 TopGolf [Member] properties	Feb. 28, 2012 Jacksonville and Indianapolis [Member] properties	Mar. 31, 2012 Highmark Member properties	Feb. 29, 2012 Basis School, Inc. [Member] First Mortgage [Member] sqft	Mar. 31, 2012 Basis School, Inc. [Member] First Mortgage [Member]	Mar. 31, 2012 Ski Resorts [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 note interest rate				9.50%				8.50%
Number of properties acquired (in properties)					2	2	2
Business acquisition purchase price					20,000,000	13,700,000	1,300,000
Commitment to fund project development						7,300,000	8,800,000
Secured first mortgage loan agreement								19,300,000
Approximate square footage of property (in square feet)								40,000
Carrying amount of mortgage note									14,300,000	42,600,000
Advanced under secure mortgage loan agreement										$ 8,900,000