Reportable Segments - Segment Net Operating Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total Net Operating Income	$ 493,720	$ 486,034	$ 431,790
Atlanta
Segment Reporting Information [Line Items]
Total Net Operating Income	177,415	172,539	158,045
Austin
Segment Reporting Information [Line Items]
Total Net Operating Income	146,923	125,215	93,311
Charlotte
Segment Reporting Information [Line Items]
Total Net Operating Income	54,645	65,203	77,082
Dallas
Segment Reporting Information [Line Items]
Total Net Operating Income	14,014	14,586	7,473
Phoenix
Segment Reporting Information [Line Items]
Total Net Operating Income	36,244	37,358	33,586
Tampa
Segment Reporting Information [Line Items]
Total Net Operating Income	38,305	33,440	37,247
Other markets
Segment Reporting Information [Line Items]
Total Net Operating Income	26,174	37,693	25,046
Office
Segment Reporting Information [Line Items]
Total Net Operating Income	488,364	481,409	428,731
Office | Atlanta
Segment Reporting Information [Line Items]
Total Net Operating Income	176,793	172,588	158,093
Office | Austin
Segment Reporting Information [Line Items]
Total Net Operating Income	146,923	125,215	93,311
Office | Charlotte
Segment Reporting Information [Line Items]
Total Net Operating Income	53,294	63,876	77,082
Office | Dallas
Segment Reporting Information [Line Items]
Total Net Operating Income	14,014	14,586	7,473
Office | Phoenix
Segment Reporting Information [Line Items]
Total Net Operating Income	36,244	37,358	37,247
Office | Tampa
Segment Reporting Information [Line Items]
Total Net Operating Income	38,305	33,440	33,586
Office | Other markets
Segment Reporting Information [Line Items]
Total Net Operating Income	22,791	34,346	21,939
Non-Office
Segment Reporting Information [Line Items]
Total Net Operating Income	5,356	4,625	3,059
Non-Office | Atlanta
Segment Reporting Information [Line Items]
Total Net Operating Income	622	(49)	(48)
Non-Office | Austin
Segment Reporting Information [Line Items]
Total Net Operating Income	0	0	0
Non-Office | Charlotte
Segment Reporting Information [Line Items]
Total Net Operating Income	1,351	1,327	0
Non-Office | Dallas
Segment Reporting Information [Line Items]
Total Net Operating Income	0	0	0
Non-Office | Phoenix
Segment Reporting Information [Line Items]
Total Net Operating Income	0	0	0
Non-Office | Tampa
Segment Reporting Information [Line Items]
Total Net Operating Income	0	0	0
Non-Office | Other markets
Segment Reporting Information [Line Items]
Total Net Operating Income	$ 3,383	$ 3,347	$ 3,107