Stock-Based Compensation and Equity - Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share Reconciliation
Net income attributable to W. P. Carey	$ 149,397	$ 41,339	$ 320,787	$ 175,871
Net income attributable to nonvested participating RSUs	0	(10)	0	(44)
Net income — basic and diluted	$ 149,397	$ 41,329	$ 320,787	$ 175,827
Weighted-average shares outstanding – basic (shares)	174,974,185	172,235,066	173,879,068	170,276,085
Effect of dilutive securities (shares)	287,627	251,440	264,970	269,580
Weighted-average shares outstanding – diluted (shares)	175,261,812	172,486,506	174,144,038	170,545,665
Potentially dilutive securities excluded from computation of diluted earning per share (share)	0	0	0	0