Segment Reporting - Income From Investment Management (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating Expenses
Reimbursable costs from affiliates	$ 968	$ 2,411	$ 2,009	$ 6,441
Subadvisor fees	0	192	0	1,469
Merger and other expenses	(2,599)	1,074	(3,075)	1,261
General and administrative	20,464	17,472	42,547	38,217
Depreciation and amortization	114,348	107,477	224,670	223,671
Stock-based compensation expense	9,048	2,918	14,429	5,579
Total operating expenses	171,185	158,379	338,088	351,366
Other Income and Expenses
(Losses) earnings from equity method investments	(156)	33,983	(9,889)	(11,807)
Other gains and (losses)	7,545	4,259	(33,643)	(5,556)
Non-operating income	3,065	4,588	9,421	9,980
Total other income and expenses	(18,958)	(9,352)	(105,791)	(100,354)
Income (loss) before income taxes	129,581	122,799	187,011	147,809
(Provision for) benefit from income taxes	(9,298)	(7,595)	(15,087)	34,097
Net Income	120,283	115,204	171,924	181,906
Net income attributable to noncontrolling interests	(38)	(9,904)	(45)	(10,516)
Net Income Attributable to W. P. Carey	120,245	105,300	171,879	171,390
Investment Management
Revenues
Gross contract revenue	4,934	6,883	9,929	21,296
Operating Expenses
Reimbursable costs from affiliates	968	2,411	2,009	6,441
Subadvisor fees	0	192	0	1,469
Merger and other expenses	0	139	15	458
General and administrative	0	0	0	5,823
Depreciation and amortization	0	0	0	987
Stock-based compensation expense	0	0	0	691
Total operating expenses	968	2,742	2,024	15,869
Other Income and Expenses
(Losses) earnings from equity method investments	1,698	33,772	3,084	(13,583)
Other gains and (losses)	73	(1,178)	1,074	(20)
Non-operating income	0	83	84	278
Total other income and expenses	1,771	32,677	4,242	(13,325)
Income (loss) before income taxes	5,737	36,818	12,147	(7,898)
(Provision for) benefit from income taxes	(179)	(3,478)	458	6,414
Net Income	5,558	33,340	12,605	(1,484)
Net income attributable to noncontrolling interests	0	(9,865)	0	(9,865)
Net Income Attributable to W. P. Carey	5,558	23,475	12,605	(11,349)
Investment Management | Asset management and other revenue
Revenues
Gross contract revenue	3,966	4,472	7,920	14,855
Investment Management | Reimbursable costs from affiliates
Revenues
Gross contract revenue	$ 968	$ 2,411	$ 2,009	$ 6,441