Equity - Basic and Diluted Earnings Per Share (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
Equity [Abstract]
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
Allocation of distribution equivalents paid on nonvested RSUs and RSAs in excess of income									(886)	(579)	(1,007)
Net income – basic									266,861	171,679	238,819
Income effect of dilutive securities, net of taxes									0	0	(77)
Net income – diluted									$ 266,861	$ 171,679	$ 238,742
Weighted-average shares outstanding – basic (shares)									106,743,012	105,675,692	98,764,164
Effect of dilutive securities (shares)									330,191	831,960	1,063,192
Weighted-average shares outstanding – diluted (shares)									107,073,203	106,507,652	99,827,356
Anti-dilutive shares									0	0	0