Investments in and Advances to Joint Ventures - Summary of Preferred investments (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) ShoppingCenter	Dec. 31, 2019 USD ($)	Dec. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)
Schedule Of Equity Method Investments [Line Items]
Preferred Investment, Valuation Allowance	$ (106.0)	$ (87.9)
BRE DDR III [Member]
Schedule Of Equity Method Investments [Line Items]
Redemption Date	2021-10
Preferred Investment (Principal)	$ 132.4			$ 300.0
Preferred Investment, Valuation Allowance	(88.2)
Preferred Investment, Net of Reserve	$ 44.2
Properties Owned | ShoppingCenter	13
BRE DDR IV [Member]
Schedule Of Equity Method Investments [Line Items]
Redemption Date	2022-12
Preferred Investment (Principal)	$ 64.0		$ 82.6
Preferred Investment, Valuation Allowance	(17.8)
Preferred Investment, Net of Reserve	$ 46.2
Properties Owned | ShoppingCenter	5
BRE DDR III and IV [Member]
Schedule Of Equity Method Investments [Line Items]
Preferred Investment (Principal)	$ 196.4		$ 382.6
Preferred Investment, Valuation Allowance	(106.0)
Preferred Investment, Net of Reserve	$ 90.4