Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	$ 206,378	$ 183,805
Total Net Operating Income	144,956	127,616
Reconciliation to net income:
Depreciation and amortization	(69,667)	(60,927)
General and administrative expenses	(13,556)	(9,952)
Interest expense	(24,393)	(19,768)
Other income	363	312
Gains on disposition of property	4,100	18,937
Equity in earnings of unconsolidated affiliates	300	637
Net income	42,103	56,855
Total Office Segment [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	205,055	180,373
Total Net Operating Income	144,137	125,675
Office Atlanta, GA [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	35,554	35,975
Total Net Operating Income	23,681	24,000
Office Charlotte, NC [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	16,944	9,134
Total Net Operating Income	13,050	7,252
Office Nashville, TN [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	43,447	35,159
Total Net Operating Income	32,522	24,993
Office Orlando, FL [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	13,312	12,559
Total Net Operating Income	8,137	7,712
Office Pittsburgh, PA [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	14,946	14,618
Total Net Operating Income	8,861	8,889
Office Raleigh, NC [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	46,296	37,042
Total Net Operating Income	34,715	28,136
Office Richmond, VA [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	10,533	11,462
Total Net Operating Income	7,225	8,053
Office Tampa, FL [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	24,023	24,424
Total Net Operating Income	15,946	16,640
Other [Member]
Segment Reporting Information [Line Items]
Total Rental and Other Revenues	1,323	3,432
Total Net Operating Income	$ 819	$ 1,941