Disposition, Acquisition, Partial Dispositions of Ownership Interests, Redevelopments, and Developments (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) ft²	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) ft² shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Feb. 14, 2019 USD ($)
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Notes payable, net (Note 8)	$ 3,710,327		$ 3,710,327	$ 3,830,195
Investment in UJVs	831,995		831,995	673,616
Gain on remeasurement of ownership interest in Unconsolidated Joint Venture			164,639
Proceeds from the Sale of Interests in Real Estate net of Transaction Costs			285,334
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes			154,466
Income Loss From Equity Method Investments Portion Due To Gain on Disposition Net of Tax					$ 2,083
Blackstone Transaction [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Expected Cash Proceeds from Agreement to Sell Partial Ownership Interests						$ 315,000
Earn Out Consideration for Agreement of Partial Sale of Ownership Interests						50,000
Equity Method Investment, Value of Ownership Interest Agreed to be Sold						$ 480,000
Starfield Anseong [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Investment in UJVs	$ 165,900		$ 165,900
Equity Method Investment, Ownership Percentage	49.00%		49.00%
Area of Real Estate Property | ft²	1,100,000		1,100,000
Country Club Plaza - Valencia Place Office Tower [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage					50.00%
Sale Price of Joint Venture Real Estate					$ 75,200
Sale Price of Joint Venture Real Estate at Beneficial Interest					37,600
Income Loss From Equity Method Investments Portion Due To Gain on Disposition Net of Tax					$ 2,100
The Gardens Mall [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Summarized Financial Information, Ownership Interest Acquired			48.50%
Noncash or Part Noncash Acquisition, Debt Assumed			$ 94,600
CityOn.Zhengzhou [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage	24.50%		24.50%	49.00%
CityOn.Zhengzhou [Member] | Blackstone Transaction [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage	24.50%		24.50%
Gain on remeasurement of ownership interest in Unconsolidated Joint Venture			$ 17,800
Equity Method Investment, Summarized Financial Information, Ownership Interest Sold			50.00%
Proceeds from the Sale of Interests in Real Estate net of Transaction Costs			$ 47,500
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes			$ 14,300
CityOn.Xi'an [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%	50.00%
CityOn.Xi'an [Member] | Blackstone Transaction [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage						25.00%
Equity Method Investment, Summarized Financial Information, Ownership Interest Agreed to be Sold						50.00%
Starfield Hanam [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage	17.15%		17.15%	34.30%
Starfield Hanam [Member] | Blackstone Transaction [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Equity Method Investment, Ownership Percentage	17.15%		17.15%
Gain on remeasurement of ownership interest in Unconsolidated Joint Venture	$ 1,800	$ 145,000
Equity Method Investment, Summarized Financial Information, Ownership Interest Sold			50.00%
Proceeds from the Sale of Interests in Real Estate net of Transaction Costs	1,800	235,700
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	$ 1,800	$ 138,700
Preferred Stock [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares			1,500,000
Preferred Stock [Member] | The Gardens Mall [Member]
Acquisition, Redevelopments, Developments, and Service Agreement [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares			1,500,000