Equity Investment in Real Estate and the Managed REITs (Narratives) (Details) (USD $)	12 Months Ended			9 Months Ended	21 Months Ended	1 Months Ended		0 Months Ended	1 Months Ended
	Dec. 31, 2014 property	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jan. 31, 2014	Jun. 30, 2013	Dec. 31, 2012	Nov. 30, 2010	Nov. 27, 2013	Dec. 31, 2007 property	Mar. 31, 2014	Sep. 28, 2012 property
Investments in REITs
Gain (loss) on sale of investment properties	$ 29,250,000	$ 39,711,000	$ (2,773,000)
Merger and property acquisition expenses	34,465,000	9,230,000	31,639,000
Income from equity method investments	44,116,000	52,731,000	62,392,000
Aggregate unamortized basis difference on equity investments	5,800,000	16,600,000
Other Transactions
Income from equity method investments	44,116,000	52,731,000	62,392,000
Number of real estate properties	783
Acquisition and Disposition of Unconsolidated Real Estate Investment
Repayments of secured debt	205,024,000	391,764,000	54,964,000
Non-recourse debt	2,532,683,000	1,492,410,000										21,023,000
Proceeds from mortgage financing	20,354,000	115,567,000	23,750,000
Equity investments in real estate	249,403,000	530,020,000
Propco
Other Transactions
Equity method investment, ownership percentage											95.00%		75.00%
Number of real estate properties													37
Real Estate Investments
Investments in REITs
Distributions received from equity investment	12,500,000	25,900,000	20,000,000
Other Transactions
Distributions received from equity investment	12,500,000	25,900,000	20,000,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	128,041,000	185,036,000
CPA: 16 - Global
Investments in REITs
Merger and property acquisition expenses		5,000,000		30,500,000	10,600,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Non-recourse debt	1,768,288,000					1,768,288,000		1,768,288,000						1,768,288,000
Equity investments in real estate	74,367,000					74,367,000		74,367,000						74,367,000
CPA: 15 - Global
Investments in REITs
Income from equity method investments			(200,000)
Other Transactions
Income from equity method investments			(200,000)
Number of real estate properties															305
Acquisition and Disposition of Unconsolidated Real Estate Investment
Non-recourse debt			1,350,755,000							1,350,755,000					1,350,755,000
Equity investments in real estate			166,247,000							166,247,000					166,247,000
CPA: 16 - Global
Investments in REITs
Distributions received from equity investment		25,300,000	24,300,000			6,400,000
Other Transactions
Equity method investment, ownership percentage	100.00%	18.533%
Distributions received from equity investment		25,300,000	24,300,000			6,400,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	0	282,520,000
CPA:16 - Global operating partnership
Investments in REITs
Distributions received from equity investment		15,200,000	15,400,000			4,800,000
Other-than-temporary impairment charges	700,000	15,400,000	9,900,000
Other Transactions
Equity method investment, ownership percentage	100.00%	0.015%
Distributions received from equity investment		15,200,000	15,400,000			4,800,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	0	813,000
CPA: 17 - Global
Investments in REITs
Asset management fees receivable, shares	240,318
Distributions received from equity investment	4,600,000	3,000,000	1,600,000
Other Transactions
Equity method investment, ownership percentage	2.676%	1.91%
Distributions received from equity investment	4,600,000	3,000,000	1,600,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	79,429,000	57,753,000
CPA: 17 - Global | Propco
Other Transactions
Increase in ownership interest in equity investments							5.00%
CPA:17 - Global operating partnership
Investments in REITs
Distributions received from equity investment	20,400,000	16,900,000	14,600,000
Other Transactions
Equity method investment, ownership percentage	0.009%	0.009%
Distributions received from equity investment	20,400,000	16,900,000	14,600,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	0	0
CPA:18 - Global
Other Transactions
Equity method investment, ownership percentage	0.221%	0.127%
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	2,784,000	320,000
CPA:18 - Global operating partnership
Investments in REITs
Distributions received from equity investment	1,800,000	100,000
Other Transactions
Equity method investment, ownership percentage	0.034%	0.034%
Distributions received from equity investment	1,800,000	100,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	209,000	209,000
CWI
Investments in REITs
Asset management fees receivable, shares	93,739
Other Transactions
Equity method investment, ownership percentage	1.088%	0.538%
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	13,940,000	3,369,000
Managed REITs
Investments in REITs
Aggregate unamortized basis difference on equity investments	20,200,000	80,500,000
Managed Programs
Investments in REITs
Gain (loss) on sale of investment properties	13,300,000	7,700,000	35,400,000
Other-than-temporary impairment charges	1,300,000	25,600,000	25,000,000
Income from equity method investments	(100,000)	(4,700,000)	(4,200,000)
Other Transactions
Income from equity method investments	(100,000)	(4,700,000)	(4,200,000)
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	121,362,000	344,984,000
Managed Programs | CPA: 15 - Global
Investments in REITs
Merger and property acquisition expenses			3,100,000
CWI operating partnership
Investments in REITs
Distributions received from equity investment	4,100,000	1,900,000
Other Transactions
Equity method investment, ownership percentage	0.015%	0.015%
Distributions received from equity investment	4,100,000	1,900,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	0	0
Carey Credit Income Fund
Other Transactions
Equity method investment, ownership percentage	50.00%	0.00%
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	25,000,000	0
Investment Owned, Shares	2,777,778
Price per share	$ 9.00
C1000 Logestiek Vastgoed B.V. | CPA: 17 - Global | Real Estate Investments
Investments in REITs
Mortgage debt tenants in common	82,700,000
Pro rata share mortgage debt on tenancy in common	12,400,000
Other Transactions
Equity method investment, ownership percentage	15.00%
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	11,192,000	13,673,000
Hellweg Die Profi-Baumarkte GmbH & Co. K.G | CPA: 16 - Global | Real Estate Investments
Acquisition and Disposition of Unconsolidated Real Estate Investment
Increase in ownership percentage of equity investments								25.00%
The New York Times Company | CPA: 16 - Global | Real Estate Investments
Acquisition and Disposition of Unconsolidated Real Estate Investment
Increase in ownership percentage of equity investments								27.00%
Beach House JV, LLC
Investments in REITs
Income from equity method investments	1,000,000
Other Transactions
Income from equity method investments	1,000,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Investment interest rate	8.50%
Redeemable preferred units owned	100
U.S. Airways Group, Inc.
Acquisition and Disposition of Unconsolidated Real Estate Investment
Repayments of secured debt									2,900,000
Non-recourse debt									17,100,000
Proceeds from mortgage financing									13,900,000
Proceeds from the sales of real estate investment									28,400,000
Gain (loss) on sale of equity investments									19,500,000
Wanbishi Archives Co. Ltd.
Acquisition and Disposition of Unconsolidated Real Estate Investment
Interest rate on debt			2.00%							2.00%
Debt maturity term										5 years
Non-recourse debt			31,600,000							31,600,000
Wanbishi Archives Co. Ltd. | Real Estate Investments
Other Transactions
Equity method investment, ownership percentage			3.00%							3.00%
Investment purchase price										1,500,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Non-recourse debt			900,000							900,000
Wanbishi Archives Co. Ltd. | CPA: 17 - Global
Other Transactions
Investment purchase price										52,100,000
Wanbishi Archives Co. Ltd. | CPA: 17 - Global | Real Estate Investments
Other Transactions
Equity method investment, ownership percentage	3.00%		97.00%							97.00%
Acquisition and Disposition of Unconsolidated Real Estate Investment
Equity investments in real estate	341,000	395,000
Medica France, S.A. | Combined Equity Investments
Investments in REITs
Gain (loss) on sale of investment properties			34,000,000
Income from equity method investments			15,100,000
Other Transactions
Income from equity method investments			15,100,000
The Talaria Company (Hinckley)
Investments in REITs
Distributions received from equity investment							4,200,000
Other Transactions
Equity method investment, ownership percentage							30.00%
Distributions received from equity investment							4,200,000
Acquisition and Disposition of Unconsolidated Real Estate Investment
Number of properties sold							5
Non-recourse debt							25,700,000
Proceeds from the sales of real estate investment							41,400,000
Gain (loss) on sale of equity investments							500,000
The Talaria Company (Hinckley) | CPA: 16 - Global
Other Transactions
Equity method investment, ownership percentage							70.00%
Hellweg 2
Investments in REITs
Income from equity method investments							(8,400,000)
Other Transactions
Income from equity method investments							(8,400,000)
Hellweg 2 | Propco
Other Transactions
Equity method investment, ownership percentage													25.00%
Real estate transfer tax							22,100,000
Increase in ownership interest in equity investments											70.00%
Hellweg 2 | CPA: 15 - Global
Other Transactions
Equity method investment, ownership percentage													40.00%
Hellweg 2 | CPA: 16 - Global
Other Transactions
Equity method investment, ownership percentage													27.00%
Hellweg 2 | CPA 14
Other Transactions
Equity method investment, ownership percentage													33.00%
Class A | CPA:18 - Global
Investments in REITs
Asset management fees receivable, shares	37,870