Real Estate Assets (Details) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($) ft²	Jun. 30, 2023 USD ($) parcel	Dec. 31, 2023 USD ($) ft² numberOfBuildings	Dec. 31, 2022 USD ($) ft² numberOfBuildings	Dec. 31, 2021 USD ($) ft² numberOfLoans numberOfOfficeBuildings numberOfBuildings
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²				28,400,000
Percentage of equity interest in joint ventures, maximum				50.00%
Dispositions [Abstract]
Gains on disposition of property				$ 47,773	$ 63,546	$ 174,059
Impairments [Abstract]
Impairments of real estate assets				0	$ 36,515	0
Raleigh NC Land Acquisition
Acquisitions [Abstract]
Purchase price of acquisition				$ 2,700
SIX50 at Legacy Union [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²					367,000
Purchase price of acquisition					$ 198,000
Charlotte NC Land Acquisition [Member]
Acquisitions [Abstract]
Purchase price of acquisition					$ 27,000
PAC Portfolio Acquisition [Member]
Acquisitions [Abstract]
Purchase price of acquisition						653,600
Capitalized acquisition costs						$ 4,500
Number of loans assumed in acquisition | numberOfLoans						4
150 Fayetteville Asset [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²						560,000
CAPTRUST Towers Asset [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²						300,000
Capitol Towers Asset [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²						479,000
Morrocroft Centre Asset [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²						291,000
Nashville TN Land Acquisitions [Member]
Acquisitions [Abstract]
Purchase price of acquisition			$ 16,000			$ 74,100
Number of development parcels acquired (in parcels) | parcel			1
Forum Portfolio Acquisition [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²						636,000
Purchase price of acquisition						$ 131,300
Percentage of partner's interest in asset acquired (in hundredths)						75.00%
Number of office properties acquired | numberOfOfficeBuildings						5
Percentage of equity interest in joint ventures, maximum						25.00%
2023 Dispostions
Dispositions [Abstract]
Number of buildings sold | numberOfBuildings				4
Sales price of disposition				$ 103,800
Gains on disposition of property				47,800
2022 Dispositions [Member]
Dispositions [Abstract]
Number of buildings sold | numberOfBuildings					5
Sales price of disposition					$ 133,500
Closing credits excluded for unfunded building and/or tenant improvements					1,100
Gains on disposition of property					$ 63,500
2021 Dispositions [Member]
Dispositions [Abstract]
Number of buildings sold | numberOfBuildings						13
Sales price of disposition						$ 384,600
Closing credits excluded for unfunded building and/or tenant improvements						6,900
Gains on disposition of property						$ 172,800
Seller Financed Transaction [Member]
Dispositions [Abstract]
Sales price of disposition				21,000
Seller Financing [Abstract]
Proceeds from sale of real estate				2,000
Non-recourse seller financing				$ 19,000
Term of debt instrument				2 years
Interest rate basis				SOFR
Interest rate, basis spread (in hundredths)				1.00%
2022 Impairments [Member]
Acquisitions [Abstract]
Rentable square feet of commercial real estate (in square feet) | ft²		616,000
Impairments [Abstract]
Impairments of real estate assets	$ 1,500	$ 35,000
Square footage occupied by customer (in sq feet) | ft²		317,000