Fair Value Measurements - Narratives (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 USD ($) property	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 USD ($) property	Dec. 31, 2019 USD ($)
Fair Value Inputs, Assets
Proceeds from the redemption of investment in shares				$ 12,522	$ 30,654
Equity investments in real estate		$ 288,444		288,444		$ 324,004
Unamortized discount		24,592		24,592
Unsecured senior notes
Fair Value Inputs, Assets
Unamortized discount		18,500		18,500
GCIF | Other assets, net
Fair Value Inputs, Assets
Unrealized investments gain (loss)				(300)
Proceeds from the redemption of investment in shares				3,700
Loss on redemption of shares				400
Equity investments in real estate		7,700		7,700		12,200
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs		0	$ 25,781	66,532	25,781
Level 3 | Carrying Value | Non-recourse mortgage, net
Fair Value Inputs, Assets
Debt instrument, unamortized discount and debt issuance costs, net		400		400		600
Unamortized discount		$ 4,800		4,800		6,200
Level 3 | Equity investments in the Managed Programs | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs				47,112	0
Level 3 | Land, buildings and improvements and intangibles | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs				19,420	0
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) | 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 3 | Net investment in direct financing leases | Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets
Recognized impairment costs		$ 0	$ 25,781	0	$ 25,781
Number of properties (property) | property			4		4
Level 2 | Carrying Value | Unsecured senior notes
Fair Value Inputs, Assets
Debt instrument, unamortized discount and debt issuance costs, net		20,300		20,300		22,800
Unamortized discount		18,500		18,500		20,500
Investment in a Cold Storage Operator | Subsequent Events
Fair Value Inputs, Assets
Payments to acquire additional interest	$ 95,500
Investment in a Cold Storage Operator | Subsequent Events | Carrying Value
Fair Value Inputs, Assets
Fair value of investments	$ 290,000
Investment in a Cold Storage Operator | Level 3
Fair Value Inputs, Assets
Unrealized investments gain (loss)		48,800		48,800
Fair value of investments		195,000		195,000		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
Preferred Stock | WLT | Level 3 | Measurement Input, Discount Rate
Fair Value Inputs, Assets
Measurement input		0.15		0.15