Segment Reporting - Income From Real Estate (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Revenues	$ 302,419	$ 318,005	$ 901,948	$ 921,539
Operating Expenses
Depreciation and amortization	108,351	109,517	332,022	335,528
General and administrative	19,399	17,210	57,616	58,224
Reimbursable tenant costs	15,728	15,611	42,699	42,699
Property expenses, excluding reimbursable tenant costs	11,923	10,377	33,649	30,204
Stock-based compensation expense	4,564	4,747	10,143	13,848
Operating property expenses	1,594	8,547	8,205	30,015
Merger and other expenses	(596)	70	665	912
Impairment charges	0	25,781	19,420	25,781
Total operating expenses	162,239	198,409	513,605	555,301
Other Income and Expenses
Interest expense	(52,537)	(58,626)	(157,259)	(179,658)
Other gains and (losses)	45,113	(12,402)	49,537	(12,118)
Gain on sale of real estate, net	20,933	71	32,684	642
Equity in earnings of equity method investments in real estate	1,720	5,769	(10,087)	15,211
Loss on change in control of interests	0	(8,416)	0	(8,416)
Total other income and expenses	15,229	(73,604)	(85,125)	(184,339)
Income before income taxes	155,409	45,992	303,218	181,899
(Provision for) benefit from income taxes	(5,975)	(4,157)	28,122	(5,147)
Net income	149,434	41,835	331,340	176,752
Net income attributable to noncontrolling interests	(37)	(496)	(10,553)	(881)
Net income attributable to W. P. Carey	149,397	41,339	320,787	175,871
Real Estate
Revenues
Lease revenues	293,856	278,839	856,269	811,580
Gross contract revenue	1,974	9,538	9,368	40,970
Lease termination income and other	1,565	14,377	9,991	23,951
Revenues	297,395	302,754	875,628	876,501
Operating Expenses
Depreciation and amortization	108,351	108,573	331,035	332,652
General and administrative	19,399	13,973	51,793	44,162
Reimbursable tenant costs	15,728	15,611	42,699	42,699
Property expenses, excluding reimbursable tenant costs	11,923	10,377	33,649	30,204
Stock-based compensation expense	4,564	3,435	9,452	9,717
Operating property expenses	1,594	8,547	8,205	30,015
Merger and other expenses	(1,016)	70	(213)	912
Impairment charges	0	25,781	19,420	25,781
Total operating expenses	160,543	186,367	496,040	516,142
Other Income and Expenses
Interest expense	(52,537)	(58,626)	(157,259)	(179,658)
Other gains and (losses)	44,777	(12,938)	48,943	(13,330)
Gain on sale of real estate, net	20,933	71	32,684	642
Equity in earnings of equity method investments in real estate	631	578	2,407	730
Loss on change in control of interests	0	(8,416)	0	(8,416)
Total other income and expenses	13,804	(79,331)	(73,225)	(200,032)
Income before income taxes	150,656	37,056	306,363	160,327
(Provision for) benefit from income taxes	(3,636)	(3,511)	24,047	(12,689)
Net income	147,020	33,545	330,410	147,638
Net income attributable to noncontrolling interests	(37)	11	(688)	94
Net income attributable to W. P. Carey	$ 146,983	$ 33,556	$ 329,722	$ 147,732