Reportable Segments - Segment Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total Revenues	$ 755,073	$ 740,340	$ 657,515
Rental property revenues
Segment Reporting Information [Line Items]
Total Revenues	739,063	721,883	628,751
Rental property revenues | Office
Segment Reporting Information [Line Items]
Total Revenues	736,365	719,866	628,751
Rental property revenues | Non-Office
Segment Reporting Information [Line Items]
Total Revenues	2,698	2,017	0
Rental property revenues | Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	767,856	750,217	681,212
Rental property revenues | Operating Segments | Atlanta
Segment Reporting Information [Line Items]
Total Revenues	270,412	256,196	242,217
Rental property revenues | Operating Segments | Austin
Segment Reporting Information [Line Items]
Total Revenues	247,806	210,229	160,196
Rental property revenues | Operating Segments | Charlotte
Segment Reporting Information [Line Items]
Total Revenues	77,402	96,537	120,214
Rental property revenues | Operating Segments | Dallas
Segment Reporting Information [Line Items]
Total Revenues	17,670	18,143	9,421
Rental property revenues | Operating Segments | Phoenix
Segment Reporting Information [Line Items]
Total Revenues	50,292	50,671	54,216
Rental property revenues | Operating Segments | Tampa
Segment Reporting Information [Line Items]
Total Revenues	59,614	54,261	51,586
Rental property revenues | Operating Segments | Other markets
Segment Reporting Information [Line Items]
Total Revenues	44,660	64,180	43,362
Rental property revenues | Operating Segments | Office
Segment Reporting Information [Line Items]
Total Revenues	758,440	742,703	676,574
Rental property revenues | Operating Segments | Office | Atlanta
Segment Reporting Information [Line Items]
Total Revenues	268,953	255,594	242,209
Rental property revenues | Operating Segments | Office | Austin
Segment Reporting Information [Line Items]
Total Revenues	247,806	210,229	160,196
Rental property revenues | Operating Segments | Office | Charlotte
Segment Reporting Information [Line Items]
Total Revenues	74,702	94,520	120,214
Rental property revenues | Operating Segments | Office | Dallas
Segment Reporting Information [Line Items]
Total Revenues	17,670	18,143	9,421
Rental property revenues | Operating Segments | Office | Phoenix
Segment Reporting Information [Line Items]
Total Revenues	50,292	50,671	51,586
Rental property revenues | Operating Segments | Office | Tampa
Segment Reporting Information [Line Items]
Total Revenues	59,614	54,261	54,216
Rental property revenues | Operating Segments | Office | Other markets
Segment Reporting Information [Line Items]
Total Revenues	39,403	59,285	38,732
Rental property revenues | Operating Segments | Non-Office
Segment Reporting Information [Line Items]
Total Revenues	9,416	7,514	4,638
Rental property revenues | Operating Segments | Non-Office | Atlanta
Segment Reporting Information [Line Items]
Total Revenues	1,459	602	8
Rental property revenues | Operating Segments | Non-Office | Austin
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Rental property revenues | Operating Segments | Non-Office | Charlotte
Segment Reporting Information [Line Items]
Total Revenues	2,700	2,017	0
Rental property revenues | Operating Segments | Non-Office | Dallas
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Rental property revenues | Operating Segments | Non-Office | Phoenix
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Rental property revenues | Operating Segments | Non-Office | Tampa
Segment Reporting Information [Line Items]
Total Revenues	0	0	0
Rental property revenues | Operating Segments | Non-Office | Other markets
Segment Reporting Information [Line Items]
Total Revenues	5,257	4,895	4,630
Rental property revenues | Segment Reconciling Items
Segment Reporting Information [Line Items]
Total Revenues	(28,793)	(28,334)	(52,461)
Rental property revenues | Segment Reconciling Items | Office
Segment Reporting Information [Line Items]
Total Revenues	(22,075)	(22,837)	(47,823)
Rental property revenues | Segment Reconciling Items | Non-Office
Segment Reporting Information [Line Items]
Total Revenues	$ (6,718)	$ (5,497)	$ (4,638)