Unconsolidated Investments - Schedule of Projects Accounted under Equity Method of Accounting (Details) - USD ($)	Sep. 30, 2019	Aug. 02, 2019	Dec. 31, 2018	Sep. 30, 2018
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 281,000,000		$ 270,000,000	$ 372,000,000
Belle River
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 32,000,000		$ 0
Percentage of Ownership	22.00%	21.70%	0.00%
North Kent
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 22,000,000		$ 0
Percentage of Ownership	35.00%	35.00%	0.00%
South Kent
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 0		$ 5,000,000
Percentage of Ownership	50.00%		50.00%
Grand
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 1,000,000		$ 5,000,000
Percentage of Ownership	45.00%		45.00%
Armow
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 104,000,000		$ 116,000,000
Percentage of Ownership	50.00%		50.00%
Pattern Development
Schedule of Equity Method Investments [Line Items]
Unconsolidated investments	$ 123,000,000		$ 144,000,000
Percentage of Ownership	29.00%		29.00%