Net Investments in Properties and Real Estate Under Construction (Narratives) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended	1 Months Ended		6 Months Ended	12 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended					12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Apr. 30, 2014 I-Shops LLC	Dec. 31, 2011 I-Shops LLC	Jun. 30, 2014 Real estate	Dec. 31, 2013 Real estate	Jun. 30, 2014 Operating real estate	Dec. 31, 2013 Operating real estate	Jun. 30, 2014 Real estate under construction property	Dec. 31, 2013 Real estate under construction property	Jun. 30, 2014 Office Building in Tucson, AZ Real estate	Jun. 30, 2014 Manufacturing facility in New Concord, Ohio Real estate	Jun. 30, 2014 BTS Six Properties Real estate under construction	Jun. 30, 2014 BTS Two Properties Real estate under construction	Jun. 30, 2014 Completed construction projects put in service property	Dec. 31, 2013 Completed construction projects put in service property	Jun. 30, 2014 Completed construction projects put in service Real estate	Dec. 31, 2013 Completed construction projects put in service Real estate	Jun. 30, 2014 Partially completed projects put in service Operating real estate	Dec. 31, 2013 Partially completed projects put in service Operating real estate
Acquisition
Investment purchase price														$ 19,000,000	$ 4,400,000
Acquired finite-lived intangible asset, amount															1,000,000
Acquisition-related cost and fees, capitalized	2,033,000	1,226,000	2,045,000	3,405,000								1,600,000	2,300,000		400,000
Land														2,500,000
Buildings														11,200,000
Acquired finite-lived intangible asset, business combination														6,000,000
Acquisition costs, expensed	272,000	724,000	1,401,000	1,795,000										1,000,000
Purchase option														600,000
Assumed non-recourse debt														10,300,000
Number of construction projects put in service													3					1	2
Capitalized funds												58,172,000	90,007,000			43,600,000	9,500,000
Transfer of assets noncash									3,500,000			57,131,000	42,225,000							42,200,000	26,100,000	14,900,000	12,600,000
Capitalized interest												3,865,000	5,208,000
Number of open construction projects												4	3
Unfunded commitments												19,900,000	46,700,000
Foreign Currency Translation
Foreign currency translation adjustments	(6,042,000)	8,612,000	(7,432,000)	(16,863,000)	29,884,000			(5,600,000)
Deconsolidation, Gain (Loss) with Related Disclosures
Potential ownership interest in entity							15.00%
Proceeds from the sales of investment			67,999,000	0		68,300,000
Net investment in properties	2,525,479,000		2,525,479,000		2,541,280,000		84,600,000	2,271,987,000	2,273,264,000	253,492,000	268,016,000
Gain on sale of real estate, net of tax	12,548,000	0	12,548,000	581,000		12,500,000
Deconsolidation of properties	55,400,000		55,400,000					27,900,000		25,800,000
Transfers from real estate owned												$ 4,800,000