Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Management:
Total revenues	$ 311,227	$ 318,005	$ 305,211	$ 298,323	$ 273,395	$ 209,384	$ 201,143	$ 201,810	$ 1,232,766	$ 885,732	$ 848,302
Operating Expenses
Depreciation and amortization									447,135	291,440	253,334
General and administrative									75,293	68,337	70,891
Reimbursable tenant costs									55,576	28,076	21,524
Property expenses, excluding reimbursable tenant costs									39,545	22,773	17,330
Operating property expenses									38,015	20,150	23,426
Impairment charges		25,800							32,539	4,790	2,769
Stock-based compensation expense									18,787	18,294	18,917
Reimbursable costs from affiliates									16,547	21,925	51,445
Subadvisor fees									7,579	9,240	13,600
Merger and other expenses									101	41,426	605
Restructuring and other compensation									0	0	9,363
Dealer manager fees and expenses									0	0	6,544
Total operating expenses	175,816	198,409	179,170	177,722	185,346	110,937	109,202	120,966	731,117	526,451	489,748
Other Income and Expenses
Interest expense									(233,325)	(178,375)	(165,775)
Other gains and (losses)									31,475	29,913	(3,613)
Equity in earnings of equity method investments in the Managed Programs and real estate									23,229	61,514	64,750
Gain on sale of real estate, net									18,143	118,605	33,878
(Loss) gain on change in control of interests		(8,400)			47,800				(8,416)	47,814	0
Total other income and expenses									(168,894)	79,471	(70,760)
Income before income taxes									332,755	438,752	287,794
Provision for income taxes									(26,211)	(14,411)	(2,711)
Net Income	129,792	41,835	66,121	68,796	195,278	81,573	79,424	68,066	306,544	424,341	285,083
Net income attributable to noncontrolling interests	(420)	(496)	(83)	(302)	(2,015)	(4,225)	(3,743)	(2,792)	(1,301)	(12,775)	(7,794)
Net Income Attributable to W. P. Carey	$ 129,372	$ 41,339	$ 66,038	$ 68,494	$ 193,263	$ 77,348	$ 75,681	$ 65,274	$ 305,243	$ 411,566	$ 277,289
Basic Earnings Per Share (usd per share)	$ 0.75	$ 0.24	$ 0.39	$ 0.41	$ 1.33	$ 0.71	$ 0.70	$ 0.60	$ 1.78	$ 3.50	$ 2.56
Diluted Earnings Per Share (usd per share)	$ 0.75	$ 0.24	$ 0.38	$ 0.41	$ 1.33	$ 0.71	$ 0.70	$ 0.60	$ 1.78	$ 3.49	$ 2.56
Weighted-Average Shares Outstanding
Basic (in shares)									171,001,430	117,494,969	107,824,738
Diluted (in shares)									171,299,414	117,706,445	108,035,971
Real Estate
Real Estate:
Lease revenues									$ 1,086,375	$ 744,498	$ 651,897
Gross contract revenue									50,220	28,072	30,562
Lease termination income and other									36,268	6,555	4,749
Investment Management:
Gross contract revenue									50,220	28,072	30,562
Total revenues									1,172,863	779,125	687,208
Operating Expenses
Depreciation and amortization									443,300	287,461	249,432
General and administrative									56,796	47,210	39,002
Reimbursable tenant costs									55,576	28,076	21,524
Property expenses, excluding reimbursable tenant costs									39,545	22,773	17,330
Operating property expenses									38,015	20,150	23,426
Impairment charges									32,539	4,790	2,769
Stock-based compensation expense									13,248	10,450	6,960
Merger and other expenses									101	41,426	605
Total operating expenses									679,120	462,336	361,048
Other Income and Expenses
Interest expense									(233,325)	(178,375)	(165,775)
Other gains and (losses)									30,251	30,015	(5,655)
Equity in earnings of equity method investments in the Managed Programs and real estate									2,361	13,341	13,068
Gain on sale of real estate, net									18,143	118,605	33,878
(Loss) gain on change in control of interests									(8,416)	18,792	0
Total other income and expenses									(190,986)	2,378	(124,484)
Income before income taxes									302,757	319,167	201,676
Provision for income taxes									(30,802)	844	(1,743)
Net Income									271,955	320,011	199,933
Net income attributable to noncontrolling interests									110	(12,775)	(7,794)
Net Income Attributable to W. P. Carey									272,065	307,236	192,139
Investment Management
Real Estate:
Gross contract revenue									59,903	106,607	161,094
Investment Management:
Gross contract revenue									59,903	106,607	161,094
Operating Expenses
Depreciation and amortization									3,835	3,979	3,902
General and administrative									18,497	21,127	31,889
Stock-based compensation expense									5,539	7,844	11,957
Reimbursable costs from affiliates									16,547	21,925	51,445
Subadvisor fees									7,579	9,240	13,600
Restructuring and other compensation									0	0	9,363
Dealer manager fees and expenses									0	0	6,544
Total operating expenses									51,997	64,115	128,700
Other Income and Expenses
Other gains and (losses)									1,224	(102)	2,042
Equity in earnings of equity method investments in the Managed Programs and real estate									20,868	48,173	51,682
(Loss) gain on change in control of interests									0	29,022	0
Total other income and expenses									22,092	77,093	53,724
Income before income taxes									29,998	119,585	86,118
Provision for income taxes									4,591	(15,255)	(968)
Net Income									34,589	104,330	85,150
Net income attributable to noncontrolling interests									(1,411)	0	0
Net Income Attributable to W. P. Carey									33,178	104,330	85,150
Investment Management | Asset management revenue
Real Estate:
Gross contract revenue									39,132	63,556	70,125
Investment Management:
Gross contract revenue									39,132	63,556	70,125
Investment Management | Reimbursable costs from affiliates
Real Estate:
Gross contract revenue									16,547	21,925	51,445
Investment Management:
Gross contract revenue									16,547	21,925	51,445
Investment Management | Structuring and other advisory revenue
Real Estate:
Gross contract revenue									4,224	21,126	35,094
Investment Management:
Gross contract revenue									4,224	21,126	35,094
Investment Management | Dealer manager fees
Real Estate:
Gross contract revenue									0	0	4,430
Investment Management:
Gross contract revenue									$ 0	$ 0	$ 4,430