Investment in Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
SUMMARY OF FINANCIAL POSITION:
Total Assets	$ 839,554		$ 779,204
Total Debt	341,384		342,892
Total Equity	358,288		338,427
Company’s Investment	146,309		140,376
SUMMARY OF OPERATIONS:
Total Revenues	25,661	$ 23,732
Net Income (Loss)	5,977	4,557
Company's Share of Income (Loss)	2,904	2,885
Terminus Office Holdings
SUMMARY OF FINANCIAL POSITION:
Total Assets	261,069		258,060
Total Debt	197,598		198,732
Total Equity	52,370		50,539
Company’s Investment	49,334		48,571
SUMMARY OF OPERATIONS:
Total Revenues	11,797	10,922
Net Income (Loss)	1,831	1,599
Company's Share of Income (Loss)	880	830
DC Charlotte Plaza LLLP
SUMMARY OF FINANCIAL POSITION:
Total Assets	175,223		155,530
Total Debt	0		0
Total Equity	89,989		88,922
Company’s Investment	47,691		46,554
SUMMARY OF OPERATIONS:
Total Revenues	410	0
Net Income (Loss)	410	0
Company's Share of Income (Loss)	205	0
Austin 300 Colorado Project, LP
SUMMARY OF FINANCIAL POSITION:
Total Assets	66,812		51,180
Total Debt	1		0
Total Equity	46,723		41,298
Company’s Investment	25,159		22,335
SUMMARY OF OPERATIONS:
Total Revenues	126	150
Net Income (Loss)	72	99
Company's Share of Income (Loss)	36	49
Carolina Square Holdings LP
SUMMARY OF FINANCIAL POSITION:
Total Assets	113,906		106,187
Total Debt	74,649		74,638
Total Equity	27,017		28,844
Company’s Investment	15,862		16,840
SUMMARY OF OPERATIONS:
Total Revenues	3,294	2,614
Net Income (Loss)	170	202
Company's Share of Income (Loss)	58	(175)
HICO Victory Center LP
SUMMARY OF FINANCIAL POSITION:
Total Assets	15,042		15,069
Total Debt	0		0
Total Equity	14,970		14,801
Company’s Investment	10,073		10,003
SUMMARY OF OPERATIONS:
Total Revenues	130	96
Net Income (Loss)	130	96
Company's Share of Income (Loss)	62	50
Charlotte Gateway Village, LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	112,218		112,553
Total Debt	0		0
Total Equity	109,190		109,666
Company’s Investment	7,987		8,225
SUMMARY OF OPERATIONS:
Total Revenues	6,743	6,772
Net Income (Loss)	2,524	2,793
Company's Share of Income (Loss)	1,262	1,397
AMCO 120 WT Holdings, LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	50,791		36,680
Total Debt	0		0
Total Equity	44,203		31,372
Company’s Investment	7,493		5,538
SUMMARY OF OPERATIONS:
Total Revenues	0	0
Net Income (Loss)	(10)	(7)
Company's Share of Income (Loss)	0	0
CL Realty, L.L.C.
SUMMARY OF FINANCIAL POSITION:
Total Assets	4,168		4,169
Total Debt	0		0
Total Equity	4,139		4,183
Company’s Investment	2,864		2,886
SUMMARY OF OPERATIONS:
Total Revenues	0	0
Net Income (Loss)	(29)	(44)
Company's Share of Income (Loss)	(22)	(28)
Temco Associates, LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	1,505		1,482
Total Debt	0		0
Total Equity	1,402		1,379
Company’s Investment	930		919
SUMMARY OF OPERATIONS:
Total Revenues	32	48
Net Income (Loss)	15	22
Company's Share of Income (Loss)	11	11
EP II LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	246		247
Total Debt	0		0
Total Equity	164		165
Company’s Investment	30		30
SUMMARY OF OPERATIONS:
Total Revenues	0	0
Net Income (Loss)	0	(5)
Company's Share of Income (Loss)	0	(4)
EP I LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	459		461
Total Debt	0		0
Total Equity	294		296
Company’s Investment	6		6
SUMMARY OF OPERATIONS:
Total Revenues	0	4
Net Income (Loss)	(2)	(16)
Company's Share of Income (Loss)	0	(12)
Wildwood Associates
SUMMARY OF FINANCIAL POSITION:
Total Assets	11,147		11,157
Total Debt	0		0
Total Equity	11,085		11,108
Company’s Investment	(472)		(460)
SUMMARY OF OPERATIONS:
Total Revenues	0	0
Net Income (Loss)	(23)	(1,000)
Company's Share of Income (Loss)	(12)	317
Crawford Long - CPI, LLC
SUMMARY OF FINANCIAL POSITION:
Total Assets	26,968		26,429
Total Debt	69,136		69,522
Total Equity	(43,258)		(44,146)
Company’s Investment	(20,648)		$ (21,071)
SUMMARY OF OPERATIONS:
Total Revenues	3,129	3,126
Net Income (Loss)	889	823
Company's Share of Income (Loss)	424	391
Other
SUMMARY OF OPERATIONS:
Total Revenues	0	0
Net Income (Loss)	0	(5)
Company's Share of Income (Loss)	$ 0	$ 59