Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	$ 207,095	$ 206,997	$ 627,138	$ 617,216
Total Net Operating Income	139,902	140,663	427,907	427,091
Reconciliation to net income:
Depreciation and amortization	(74,765)	(73,057)	(220,416)	(212,466)
Impairments of real estate assets	0	(1,515)	0	(36,515)
General and administrative expenses	(8,873)	(9,586)	(30,668)	(32,733)
Interest expense	(34,247)	(26,392)	(101,408)	(75,812)
Other income	754	138	3,082	621
Gains on disposition of property	0	9,402	19,818	63,546
Gain on deconsolidation of affiliate	0	0	11,778	0
Equity in earnings of unconsolidated affiliates	400	457	1,902	1,083
Net income	23,171	40,110	111,995	134,815
Total Office Segment [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	193,085	192,532	584,207	570,443
Total Net Operating Income	132,137	132,103	403,965	399,130
Office Atlanta, GA [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	35,666	35,804	107,991	106,805
Total Net Operating Income	21,796	22,524	68,289	69,472
Office Charlotte, NC [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	21,079	18,825	63,452	52,643
Total Net Operating Income	16,388	14,275	47,719	40,132
Office Nashville, TN [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	42,884	44,587	130,084	130,640
Total Net Operating Income	31,389	33,154	95,530	97,093
Office Orlando, FL [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	14,356	13,634	43,300	40,298
Total Net Operating Income	8,734	7,865	26,358	24,264
Office Raleigh, NC [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	45,354	45,220	136,933	137,051
Total Net Operating Income	32,523	32,822	99,799	101,557
Office Richmond, VA [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	8,746	10,872	27,103	31,837
Total Net Operating Income	5,733	7,112	18,656	21,700
Office Tampa, FL [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	25,000	23,590	75,344	71,169
Total Net Operating Income	15,574	14,351	47,614	44,912
Other [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	14,010	14,465	42,931	46,773
Total Net Operating Income	$ 7,765	$ 8,560	$ 23,942	$ 27,961