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Represents the number of office properties sold.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Amount after tax of income (loss) from operations classified as a discontinued operation. Excludes gain (loss) on disposal and provision for gain (loss) until disposal.

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Amount of depreciation and amortization expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of operating expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of revenue attributable to disposal group, including, but not limited to, discontinued operation.

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The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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The cash inflow from the sale of formerly productive land held for sale, anything permanently fixed to it, including buildings, structures on it, and so forth.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Dispositions of Property (Details)														3 Months Ended		9 Months Ended	12 Months Ended
Dispositions of Property (Details)	Jan. 26, 2024 USD ($)	Dec. 06, 2023 USD ($)	Oct. 26, 2023 USD ($)	Aug. 09, 2023 USD ($) property	Mar. 10, 2023 USD ($) property	Dec. 28, 2022 USD ($)	Aug. 31, 2022 USD ($) property	Nov. 16, 2021 USD ($) property	Oct. 22, 2021 USD ($)	Sep. 23, 2021 USD ($) property	Aug. 31, 2021 USD ($)	Jun. 29, 2021 USD ($)	May 27, 2021 USD ($) property	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) ft²	Sep. 30, 2023 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Dispositions of Property
Assets Held-for-sale, Not Part of Disposal Group														$ 73,318,000			$ 73,318,000
Real estate assets														890,824,000			890,824,000	$ 1,103,248,000
Straight-line rent receivable														40,397,000			40,397,000	52,739,000
Deferred leasing commissions														23,664,000			23,664,000	35,709,000
Operating results for discontinued operations:
Rental revenue																	27,157,000	43,025,000	$ 84,179,000
Rental operating expenses																	(8,449,000)	(13,256,000)	(23,547,000)
Real estate taxes and insurance																	(4,103,000)	(10,228,000)	(17,150,000)
Depreciation and amortization																	(7,206,000)	(14,656,000)	(27,025,000)
Income from dispositions and assets held for sale																	7,399,000	$ 4,885,000	$ 16,457,000
Office properties in Broomfield, Colorado
Dispositions of Property
Number of properties sold \| property							2
Gain (loss) on sale of property							$ 24,100,000
Sale price							$ 102,500,000
Property in Atlanta, Georgia
Dispositions of Property
Number of properties sold \| property													3
Assets Held-for-sale, Not Part of Disposal Group														39,000,000.0	$ 40,000,000.0	$ 40,000,000.0	39,000,000.0
Gain (loss) on sale of property									$ 86,800,000				$ 22,800,000
Sale price									$ 223,900,000				$ 219,500,000
Real estate assets														52,200,000			52,200,000
Straight-line rent receivable														4,400,000			4,400,000
Deferred leasing commissions														2,900,000			2,900,000
Impairment charge																20,500,000
Office Property in Dulles, Virginia
Dispositions of Property
Gain (loss) on sale of property												$ (2,100,000)
Sale price												$ 17,300,000
Office property in Indianapolis, Indiana
Dispositions of Property
Gain (loss) on sale of property											$ (1,700,000)
Sale price											$ 35,000,000
Office Property in Evanston, Illinois
Dispositions of Property
Gain (loss) on sale of property						$ 3,900,000
Sale price						$ 27,800,000
Office properties in Chesterfield, MO
Dispositions of Property
Number of properties sold \| property										2
Gain (loss) on sale of property										$ 10,300,000
Sale price										$ 67,000,000
Office property in Chantilly, VA
Dispositions of Property
Number of properties sold \| property								2
Gain (loss) on sale of property								$ (2,900,000)
Sale price								$ 40,000,000
Property in Plano, Texas
Dispositions of Property
Assets Held-for-sale, Not Part of Disposal Group															36,200,000	$ 36,200,000
Gain (loss) on sale of property			$ 10,600,000												10,600,000
Sale price			$ 48,000,000.0												48,000,000.0
Office Property in Charlotte, North Carolina
Dispositions of Property
Number of properties sold \| property				1
Gain (loss) on sale of property				$ (800,000)
Sale price				$ 9,200,000
Office Property in Elk Grove Village, Illinois
Dispositions of Property
Number of properties sold \| property					1
Gain (loss) on sale of property					$ 8,400,000
Sale price					$ 29,100,000
Property in Addison, Texas
Dispositions of Property
Gain (loss) on sale of property															$ 53,000
Area of property (in square feet) \| ft²															7,826	7,826
Property in Miami, Florida
Dispositions of Property
Gain (loss) on sale of property		$ (18,900,000)
Sale price		$ 68,000,000.0
Properties in Miami, Florida and Atlanta, Georgia
Dispositions of Property
Assets Held-for-sale, Not Part of Disposal Group															$ 96,400,000	$ 96,400,000
Impairment charge															39,700,000
Properties In Richardson, Texas
Dispositions of Property
Assets Held-for-sale, Not Part of Disposal Group														34,400,000			34,400,000
Sale price															$ 35,000,000.0
Real estate assets														31,100,000			31,100,000
Straight-line rent receivable														3,400,000			3,400,000
Deferred leasing commissions														2,000,000.0			$ 2,000,000.0
Impairment charge														$ 2,100,000
Properties In Richardson, Texas \| Subsequent event
Dispositions of Property
Gain (loss) on sale of property	$ (2,100,000)
Sale price	$ 35,000,000