Segment Reporting - Income by Geography (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
Segment Reporting Information Profit Loss
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	(144,564)	(136,472)	(160,697)	(180,000)	(150,902)	(159,066)	(130,382)	(140,479)	(621,733)	(580,829)	(637,378)
Interest expense									(183,409)	(194,326)	(178,122)
Provision for income taxes									(3,288)	(37,621)	(17,609)
Gain (loss) on sale of real estate, net of tax		49,100
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)
Income from continuing operations attributable to W. P. Carey									267,747	172,258	206,329
Real Estate Ownership
Segment Reporting Information Profit Loss
Revenues									755,364	735,448	645,383
Operating expenses									(453,667)	(426,814)	(404,674)
Interest expense									(183,409)	(194,326)	(178,122)
Other income and expenses, excluding interest expense									66,389	54,924	135,558
Provision for income taxes									3,418	(17,948)	916
Gain (loss) on sale of real estate, net of tax									71,318	6,487	1,581
Net income attributable to noncontrolling interests									(7,060)	(10,961)	(5,573)
Net (loss) income attributable to noncontrolling interests of discontinued operations									0	0	(179)
Income from continuing operations attributable to W. P. Carey									252,353	146,810	194,890
Real Estate Ownership | UNITED STATES
Segment Reporting Information Profit Loss
Revenues									490,134	468,703	426,578
Operating expenses									(274,013)	(296,265)	(284,362)
Interest expense									(149,615)	(153,219)	(117,603)
Other income and expenses, excluding interest expense									59,683	50,891	146,156
Provision for income taxes									(4,808)	(6,219)	(3,238)
Gain (loss) on sale of real estate, net of tax									56,492	2,941	(5,119)
Net income attributable to noncontrolling interests									(7,591)	(5,358)	(4,233)
Net (loss) income attributable to noncontrolling interests of discontinued operations									0	0	(179)
Income from continuing operations attributable to W. P. Carey									170,282	61,474	158,000
Real Estate Ownership | Germany
Segment Reporting Information Profit Loss
Revenues									68,372	65,777	72,978
Operating expenses									(28,473)	818	(40,847)
Interest expense									(15,681)	(15,432)	(18,880)
Other income and expenses, excluding interest expense									649	4,175	(10,698)
Provision for income taxes									(4,083)	(4,357)	3,163
Gain (loss) on sale of real estate, net of tax									0	21	0
Net income attributable to noncontrolling interests									252	(5,537)	(1,017)
Income from continuing operations attributable to W. P. Carey									21,036	45,465	4,699
Real Estate Ownership | Other International
Segment Reporting Information Profit Loss
Revenues									196,858	200,968	145,827
Operating expenses									(151,181)	(131,367)	(79,465)
Interest expense									(18,113)	(25,675)	(41,639)
Other income and expenses, excluding interest expense									6,057	(142)	100
Provision for income taxes									12,309	(7,372)	991
Gain (loss) on sale of real estate, net of tax									14,826	3,525	6,700
Net income attributable to noncontrolling interests									279	(66)	(323)
Income from continuing operations attributable to W. P. Carey									$ 61,035	$ 39,871	$ 32,191