Fair Value Measurements - Narratives (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) property	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) property	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Inputs, Assets
Proceeds from the redemption of investment in shares			$ 10,463	$ 27,186
Equity investments in real estate	$ 284,643		284,643		$ 324,004
Unamortized discount	25,219		25,219
Unsecured senior notes
Fair Value Inputs, Assets
Unamortized discount	18,800		18,800
GCIF | Other assets, net
Fair Value Inputs, Assets
Proceeds from the redemption of investment in shares			3,500
Loss on redemption of shares			400
Unrealized investments loss	(800)		(800)
Equity investments in real estate	7,600		7,600		12,200
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs	0	$ 66,532
Level 3 | Carrying Value | Non-Recourse Debt
Fair Value Inputs, Assets
Unamortized discount	5,100		5,100		6,200
Level 3 | Carrying Value | Non recourse mortgage
Fair Value Inputs, Assets
Debt instrument, unamortized discount and debt issuance costs, net	500		500		600
Level 3 | Equity investments in the Managed Programs | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs	0	47,112
Level 3 | Land, buildings and improvements and intangibles | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs	$ 0	$ 19,420
Level 3 | Land, buildings and improvements and intangibles | Fair Value, Measurements, Nonrecurring | Potentially vacant properties
Fair Value Inputs, Assets
Recognized impairment costs			$ 16,000
Number of Properties | property	2		2
Level 3 | Land, buildings and improvements and intangibles | Fair Value, Measurements, Nonrecurring | Impaired property
Fair Value Inputs, Assets
Recognized impairment costs			$ 3,400
Level 2 | Carrying Value | Unsecured senior notes
Fair Value Inputs, Assets
Debt instrument, unamortized discount and debt issuance costs, net	$ 20,800		20,800		22,800
Unamortized discount	18,800		18,800		20,500
Investment in a Cold Storage Operator | Level 3
Fair Value Inputs, Assets
Fair value of investments	146,200		146,200		146,200
CWI 1 | Affiliated Entity
Fair Value Inputs, Assets
Equity investments in real estate	0		0		49,032
CWI 1 | Level 3 | Equity investments in the Managed Programs | Fair Value, Measurements, Nonrecurring | Affiliated Entity
Fair Value Inputs, Assets
Recognized impairment costs			27,800
CWI 2 | Affiliated Entity
Fair Value Inputs, Assets
Equity investments in real estate	0		0		$ 33,669
CWI 2 | Level 3 | Equity investments in the Managed Programs | Fair Value, Measurements, Nonrecurring | Affiliated Entity
Fair Value Inputs, Assets
Recognized impairment costs			19,300
Preferred Stock | WLT | Level 3
Fair Value Inputs, Assets
Equity method investment fair value	$ 46,300		$ 46,300