Real Estate Assets (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2022 USD ($) ft² numberOfJointVentures numberOfMarkets	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) ft² numberOfJointVentures numberOfMarkets	Jun. 30, 2021 USD ($)
Dispositions [Abstract]
Gains on disposition of property	$ 50,044		$ 22,862	$ 54,144	$ 41,799
Impairments [Abstract]
Rentable square feet of commercial real estate office properties under development (in sq feet) | ft²	600,000			600,000
Impairments of real estate assets	$ 35,000		$ 0	$ 35,000	$ 0
Charlotte Land Acquisition [Member]
Acquisitions [Abstract]
Acquisition purchase price	27,000
2022 Dispositions [Member]
Dispositions [Abstract]
Sale price of real estate	100,700	$ 9,600
Closing credits excluded	1,100
Gains on disposition of property	$ 50,000	$ 4,100
Dallas Joint Ventures [Member]
Impairments [Abstract]
Number of joint ventures formed | numberOfJointVentures	2			2
Number of submarkets entered | numberOfMarkets	2			2
Pittsburgh Division Office [Member]
Impairments [Abstract]
Rentable square feet of commercial real estate office properties under development (in sq feet) | ft²	2,155,000			2,155,000
Percent of NOI (in hundredths)	6.00%			6.00%
Percentage of rentable square feet occupied (in hundredths)	92.90%			92.90%
EQT Plaza Impairment [Member]
Impairments [Abstract]
Rentable square feet of commercial real estate office properties under development (in sq feet) | ft²	616,000			616,000
Impairments of real estate assets	$ 35,000
Square footage occupied by customer (in sq ft) | ft²	317,000			317,000