Segment Reporting - Income From Investment Management (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investment Management:
Asset management revenue	$ 16,985	$ 17,367
Reimbursable costs from affiliates	5,304	25,700
Structuring revenue	1,739	3,834
Other advisory revenue	190	91
Dealer manager fees	0	3,325
Total revenues	201,810	219,059
Operating Expenses
General and administrative	18,583	18,424
Reimbursable tenant and affiliate costs	11,523	30,921
Stock-based compensation expense	8,219	6,910
Subadvisor fees	2,032	2,720
Depreciation and amortization	65,957	62,430
Dealer manager fees and expenses	0	3,294
Total operating expenses	120,966	134,882
Other Income and Expenses
Equity in earnings of equity method investments in the Managed Programs and real estate	15,325	15,774
Other gains and (losses)	(2,763)	516
Total other income and expenses	(25,512)	(25,667)
Income before income taxes and gain on sale of real estate	55,332	58,510
Benefit from income taxes	6,002	1,305
Net Income Attributable to W. P. Carey	65,274	57,484
Investment Management
Investment Management:
Asset management revenue	16,985	17,367
Reimbursable costs from affiliates	5,304	25,700
Structuring revenue	1,739	3,834
Other advisory revenue	190	91
Dealer manager fees	0	3,325
Total revenues	24,218	50,317
Operating Expenses
General and administrative	6,518	10,150
Reimbursable tenant and affiliate costs	5,304	25,700
Stock-based compensation expense	3,913	4,956
Subadvisor fees	2,032	2,720
Depreciation and amortization	1,037	908
Dealer manager fees and expenses	0	3,294
Total operating expenses	18,804	47,728
Other Income and Expenses
Equity in earnings of equity method investments in the Managed Programs and real estate	11,967	13,702
Other gains and (losses)	124	476
Total other income and expenses	12,091	14,178
Income before income taxes and gain on sale of real estate	17,505	16,767
Benefit from income taxes	2,469	2,759
Net Income Attributable to W. P. Carey	$ 19,974	$ 19,526