Net Investments in Properties (Narratives) (Details) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended							9 Months Ended			9 Months Ended	0 Months Ended
	Sep. 30, 2014 property	Sep. 30, 2013	Sep. 30, 2014 property	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Direct financing lease	Sep. 30, 2014 Assets held-for-sale	Dec. 31, 2013 Assets held-for-sale property	Sep. 30, 2014 CPA: 16 - Global	Mar. 31, 2014 CPA: 16 - Global	Jan. 31, 2014 CPA: 16 - Global	Sep. 30, 2014 CPA: 16 - Global Assets held-for-sale property	Sep. 30, 2014 Real estate	Dec. 31, 2013 Real estate	Sep. 30, 2014 Real estate CPA: 16 - Global property	Sep. 30, 2014 Business combination	Mar. 26, 2014 Business combination Office building in Chandler, AZ	May 15, 2014 Business combination Distribution facility in University Park, IL	Aug. 06, 2014 Business combination Office building in Stavanger, Norway	Aug. 22, 2014 Business combination Office building Westborough, MA	Sep. 30, 2014 Hotel property	Sep. 30, 2014 Self-storage property
Real Estate Properties
Decrease in exchange rate	7.90%		7.90%
Foreign currency exchange rate	1.2687		1.2687		1.3768
Decrease in value of balance sheet item due to foreign currency translation	$ 55,096,000	$ (17,675,000)	$ 52,140,000	$ (13,017,000)		$ 32,600,000							$ 81,300,000
Number of real estate properties	688		688					9							225						2	2
Net investments in properties	4,413,268,000		4,413,268,000		2,353,391,000				1,970,175,000	1,969,274,000	1,970,175,000		4,332,372,000	2,348,249,000
Reclassification to real estate owned						13,700,000
Reclassification from real estate owned							1,300,000
Investments in real estate
Investment purchase price																252,000,000	41,900,000	47,200,000	116,900,000	46,000,000
Land acquired																26,900,000
Buildings acquired																188,300,000
Acquired finite-lived intangible asset, business combination																36,800,000
Deferred tax liability																			14,600,000
Goodwill allocated	702,791,000		702,791,000		350,208,000				348,876,000	348,972,000	348,876,000								11,700,000
Acquisition costs, expensed																800,000
Assets Held For Sale
Number of properties sold												10
Assets held for sale	$ 0		$ 0		$ 86,823,000				$ 133,415,000	$ 132,951,000	$ 133,415,000