Segment Reporting - Income From Investment Management (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment Management:
Reimbursable costs from affiliates									$ 66,433	$ 55,837	$ 130,212
Asset management revenue									61,971	49,984	38,063
Structuring revenue									47,328	92,117	71,256
Dealer manager fees									8,002	4,794	23,532
Other advisory revenue									2,435	203	0
Total revenues	$ 228,780	$ 225,247	$ 217,266	$ 270,240	$ 265,250	$ 214,666	$ 238,079	$ 220,388	941,533	938,383	908,446
Operating Expenses
General and administrative									82,352	103,172	91,588
Subadvisor fees									14,141	11,303	5,501
Dealer manager fees and expenses									12,808	11,403	21,760
Stock-based compensation expense									18,015	21,626	31,075
Restructuring and other compensation									11,925	0	0
Depreciation and amortization									276,510	280,315	237,123
Merger, property acquisition, and other expenses									5,377	(7,764)	34,465
Total operating expenses	144,564	136,472	160,697	180,000	150,902	159,066	130,382	140,479	621,733	580,829	637,378
Other Income and Expenses
Other income and (expenses)									5,667	2,113	(14,230)
Income from equity method investments									64,719	51,020	44,116
Total other income and expenses									(113,023)	(141,193)	(42,289)
Income from continuing operations before income taxes and gain on sale of real estate									206,777	216,361	228,779
Provision for income taxes									(3,288)	(37,621)	(17,609)
Net Income	48,470	112,302	53,171	60,864	56,144	23,578	66,923	38,582	274,807	185,227	246,069
Net income attributable to noncontrolling interests	(766)	(1,359)	(1,510)	(3,425)	(5,095)	(1,833)	(3,575)	(2,466)	(7,060)	(12,969)	(6,385)
Net loss attributable to redeemable noncontrolling interest									0	0	142
Net Income Attributable to W. P. Carey	$ 47,704	$ 110,943	$ 51,661	$ 57,439	$ 51,049	$ 21,745	$ 63,348	$ 36,116	267,747	172,258	239,826
Investment Management
Investment Management:
Reimbursable costs from affiliates									66,433	55,837	130,212
Asset management revenue									61,971	49,984	38,063
Structuring revenue									47,328	92,117	71,256
Dealer manager fees									8,002	4,794	23,532
Other advisory revenue									2,435	203	0
Total revenues									186,169	202,935	263,063
Operating Expenses
General and administrative									47,761	55,496	52,791
Subadvisor fees									14,141	11,303	5,501
Dealer manager fees and expenses									12,808	11,403	21,760
Stock-based compensation expense									12,791	13,753	18,416
Restructuring and other compensation									7,512	0	0
Depreciation and amortization									4,236	4,079	4,024
Merger, property acquisition, and other expenses									2,384	2,144	0
Total operating expenses									168,066	154,015	232,704
Other Income and Expenses
Other income and (expenses)									2,002	161	275
Income from equity method investments									1,995	(1,952)	0
Total other income and expenses									3,997	(1,791)	275
Income from continuing operations before income taxes and gain on sale of real estate									22,100	47,129	30,634
Provision for income taxes									(6,706)	(19,673)	(18,525)
Net Income									15,394	27,456	12,109
Net income attributable to noncontrolling interests									0	(2,008)	(812)
Net loss attributable to redeemable noncontrolling interest									0	0	142
Net Income Attributable to W. P. Carey									$ 15,394	$ 25,448	$ 11,439