Equity Investments in Real Estate (Narratives) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Equity Investments in Real Estate
Net income from equity investments in real estate	$ 513,000	$ 954,000	$ 3,380,000	$ 5,220,000
Footnote Details
Non-recourse mortgage loans	178,200,000		178,200,000
Acquisition-related cost and fees, capitalized	3,284,000	6,636,000	6,689,000	16,568,000
Capital contributions to equity investments			93,115,000	7,890,000
Net income from equity investments in real estate	513,000	954,000	3,380,000	5,220,000
Hellweg Die Profi Baumarkt Gmbh And Co KG
Footnote Details
Equity method investments, distributions (return of capital)			1,300,000	2,300,000
State Farm Mutual Automobile Company
Footnote Details
Purchase price of equity method investment	115,600,000		115,600,000
Share of the purchase price of equity method investment	57,800,000		57,800,000
Non-recourse mortgage loans	72,800,000		72,800,000
Non-recourse mortgage loan interest rate	4.50%		4.50%
Share of the non-recourse debt	36,400,000		36,400,000
Non-recourse mortgage loan maturity date			Sep. 01, 2023
Acquisition-related cost and fees, capitalized			5,600,000
Berry Plastics Corporation
Footnote Details
Equity method investments, distributions (return of capital)			1,800,000	1,700,000
C1000 Logistiek Vastgooed B.V
Footnote Details
Non-recourse mortgage loans	94,400,000		94,400,000
Share of the non-recourse debt	80,200,000		80,200,000
Equity method investments, distributions (return of capital)			4,700,000	8,200,000
Equity method investment, additional information			For this investment, the co-obligor is WPC and the total amount due under the arrangement was approximately $94.4 million at September 30, 2013. Of this amount, $80.2 million represents the amount we agreed to pay and is included within the carrying value of this investment.
Shelborne
Footnote Details
Capitalized funds	45,300,000		45,300,000
Unfunded commitments	18,700,000		18,700,000
I-Drive Live
Footnote Details
Capitalized funds	3,700,000		3,700,000
Unfunded commitments	$ 44,500,000		$ 44,500,000