Reportable Segments - Net Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net Operating Income	$ 123,124	$ 127,782
Atlanta
Segment Reporting Information [Line Items]
Net Operating Income	43,196	44,795
Austin
Segment Reporting Information [Line Items]
Net Operating Income	34,278	29,294
Charlotte
Segment Reporting Information [Line Items]
Net Operating Income	15,257	22,113
Dallas
Segment Reporting Information [Line Items]
Net Operating Income	3,551	3,639
Phoenix
Segment Reporting Information [Line Items]
Net Operating Income	9,025	9,793
Tampa
Segment Reporting Information [Line Items]
Net Operating Income	9,402	8,144
Other
Segment Reporting Information [Line Items]
Net Operating Income	8,415	10,004
Office
Segment Reporting Information [Line Items]
Net Operating Income	122,099	126,966
Office | Atlanta
Segment Reporting Information [Line Items]
Net Operating Income	43,045	44,855
Office | Austin
Segment Reporting Information [Line Items]
Net Operating Income	34,278	29,294
Office | Charlotte
Segment Reporting Information [Line Items]
Net Operating Income	15,257	22,113
Office | Dallas
Segment Reporting Information [Line Items]
Net Operating Income	3,551	3,639
Office | Phoenix
Segment Reporting Information [Line Items]
Net Operating Income	9,025	9,793
Office | Tampa
Segment Reporting Information [Line Items]
Net Operating Income	9,402	8,144
Office | Other
Segment Reporting Information [Line Items]
Net Operating Income	7,541	9,128
Mixed-Use
Segment Reporting Information [Line Items]
Net Operating Income	1,025	816
Mixed-Use | Atlanta
Segment Reporting Information [Line Items]
Net Operating Income	151	(60)
Mixed-Use | Austin
Segment Reporting Information [Line Items]
Net Operating Income	0	0
Mixed-Use | Charlotte
Segment Reporting Information [Line Items]
Net Operating Income	0	0
Mixed-Use | Dallas
Segment Reporting Information [Line Items]
Net Operating Income	0	0
Mixed-Use | Phoenix
Segment Reporting Information [Line Items]
Net Operating Income	0	0
Mixed-Use | Tampa
Segment Reporting Information [Line Items]
Net Operating Income	0	0
Mixed-Use | Other
Segment Reporting Information [Line Items]
Net Operating Income	$ 874	$ 876