Dispositions and Impairment - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 28, 2019 USD ($)	Dec. 31, 2018 property	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property building
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate gain on sale of properties			$ 139,039	$ 250,889	$ 252,913
Number of real estate properties | property			130
Properties classified as held-for-sale (in number of properties) | property			2	0
Asset impairment charges			$ 14,460	$ 5,329	95,813
Number of impaired properties | property			4
Properties Conveyed to Lenders
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties | property			3
Gain (loss) on debt extinguishment on sale of properties			$ 34,450
Disposal Group, Disposed of by Sale, not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of property			432,843	504,118	898,514
Aggregate gain on sale of properties			139,039	250,889	252,913
Gain (loss) on debt extinguishment on sale of properties			$ 2,879	4,415	$ 1,698
Office Building
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate gain on sale of properties	$ 824
Number of properties sold | property		6
Asset impairment charges				2,974
Number of impaired properties | property					2
Impairment of assets held-for-use					$ 23,496
Retail Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset impairment charges				$ 2,106
Number of impaired properties | property				2
Properties Held at Fiscal Year End
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of assets held-for-use					$ 36,620
NNN Office Joint Venture Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate gain on sale of properties				$ 3,529
NNN Office Joint Venture Properties | Transferred Property | Office Building | Disposal Group, Disposed of by Sale, not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | building					21