Segment Reporting - Income From Investment Management (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Expenses
Reimbursable costs from affiliates	$ 2,411	$ 3,821	$ 6,441	$ 7,689
Subadvisor fees	192	1,650	1,469	3,852
Merger and other expenses	1,074	696	1,261	842
General and administrative	17,472	19,729	38,217	41,014
Stock-based compensation expense	2,918	4,936	5,579	9,101
Depreciation and amortization	107,477	113,632	223,671	226,011
Total operating expenses	158,379	179,170	351,366	356,892
Other Income and Expenses
Equity in earnings of equity method investments in real estate	33,983	3,951	(11,807)	9,442
Other gains and (losses)	8,847	(671)	4,424	284
Total other income and expenses	(9,352)	(56,801)	(100,354)	(110,735)
Income before income taxes	122,799	69,240	147,809	135,907
(Provision for) benefit from income taxes	(7,595)	(3,119)	34,097	(990)
Net Income	115,204	66,121	181,906	134,917
Net income attributable to noncontrolling interests	(9,904)	(83)	(10,516)	(385)
Net Income Attributable to W. P. Carey	105,300	66,038	171,390	134,532
Investment Management
Revenues
Gross contract revenue	6,883	13,669	21,296	29,787
Operating Expenses
Reimbursable costs from affiliates	2,411	3,821	6,441	7,689
Subadvisor fees	192	1,650	1,469	3,852
Merger and other expenses	139	0	458	0
General and administrative	0	4,728	5,823	10,825
Stock-based compensation expense	0	1,454	691	2,819
Depreciation and amortization	0	966	987	1,932
Total operating expenses	2,742	12,619	15,869	27,117
Other Income and Expenses
Equity in earnings of equity method investments in real estate	33,772	3,721	(13,583)	9,290
Other gains and (losses)	(1,095)	691	258	676
Total other income and expenses	32,677	4,412	(13,325)	9,966
Income before income taxes	36,818	5,462	(7,898)	12,636
(Provision for) benefit from income taxes	(3,478)	(100)	6,414	8,188
Net Income	33,340	5,362	(1,484)	20,824
Net income attributable to noncontrolling interests	(9,865)	(92)	(9,865)	(468)
Net Income Attributable to W. P. Carey	23,475	5,270	(11,349)	20,356
Investment Management | Asset management revenue
Revenues
Gross contract revenue	4,472	9,790	14,361	19,522
Investment Management | Reimbursable costs from affiliates
Revenues
Gross contract revenue	2,411	3,821	6,441	7,689
Investment Management | Structuring and other advisory revenue
Revenues
Gross contract revenue	$ 0	$ 58	$ 494	$ 2,576