Segment Reporting - Income From Real Estate (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Revenues	$ 209,384	$ 210,754	$ 612,337	$ 651,341
Operating Expenses
Depreciation and amortization	67,825	64,040	198,119	189,319
General and administrative	15,863	17,236	50,888	53,189
Property expenses, excluding reimbursable tenant costs	7,953	10,556	26,760	31,196
Reimbursable tenant and affiliate costs	12,021	11,608	34,814	61,330
Merger and other expenses	1,673	65	4,328	1,138
Stock-based compensation expense	2,475	4,635	14,392	14,649
Impairment charges	0	0	4,790	0
Total operating expenses	110,937	115,164	341,105	378,037
Other Income and Expenses
Interest expense	(41,740)	(41,182)	(121,125)	(125,374)
Equity in earnings of equity method investments in the Managed Programs and real estate	18,363	16,318	46,246	47,820
Other gains and (losses)	8,875	(4,569)	16,698	(4,969)
Total other income and expenses	(14,502)	(29,433)	(58,181)	(82,523)
Income before income taxes and gain on sale of real estate	83,945	66,157	213,051	190,781
(Provision for) benefit from income taxes	(2,715)	(1,760)	(2,975)	(2,903)
Income before gain on sale of real estate	81,230	64,397	210,076	187,878
Gain on sale of real estate, net of tax	343	19,257	18,987	22,732
Net Income	81,573	83,654	229,063	210,610
Net income attributable to noncontrolling interests	(4,225)	(3,376)	(10,760)	(8,530)
Net Income Attributable to W. P. Carey	77,348	80,278	218,303	202,080
Real Estate
Revenues
Lease revenues	167,088	161,511	492,935	475,547
Reimbursable tenant costs	5,979	5,397	17,931	15,940
Lease termination income and other	1,981	1,227	3,603	4,234
Revenues	179,330	176,584	530,834	519,373
Operating Expenses
Depreciation and amortization	66,837	62,970	195,131	186,481
General and administrative	11,349	11,234	34,013	27,311
Property expenses, excluding reimbursable tenant costs	7,953	10,556	26,760	31,196
Reimbursable tenant and affiliate costs	5,979	5,397	17,931	15,940
Merger and other expenses	1,673	65	4,328	1,138
Stock-based compensation expense	1,380	1,880	7,676	4,733
Impairment charges	0	0	4,790	0
Total operating expenses	95,171	92,102	290,629	266,799
Other Income and Expenses
Interest expense	(41,740)	(41,182)	(121,125)	(125,374)
Equity in earnings of equity method investments in the Managed Programs and real estate	4,699	3,740	11,586	9,533
Other gains and (losses)	8,197	(4,918)	14,940	(6,249)
Total other income and expenses	(28,844)	(42,360)	(94,599)	(122,090)
Income before income taxes and gain on sale of real estate	55,315	42,122	145,606	130,484
(Provision for) benefit from income taxes	(424)	(1,511)	1,792	(6,696)
Income before gain on sale of real estate	54,891	40,611	147,398	123,788
Gain on sale of real estate, net of tax	343	19,257	18,987	22,732
Net Income	55,234	59,868	166,385	146,520
Net income attributable to noncontrolling interests	(4,225)	(3,376)	(10,760)	(8,530)
Net Income Attributable to W. P. Carey	51,009	56,492	155,625	137,990
Real Estate | Operating property revenues
Revenues
Gross contract revenue	$ 4,282	$ 8,449	$ 16,365	$ 23,652