Investment in Unconsolidated Joint Ventures - Summary of Financial Position and Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
SUMMARY OF FINANCIAL POSITION:
Total Assets	$ 6,945,970		$ 6,945,970		$ 7,107,398
Total Equity (Deficit)	4,435,863		4,435,863		4,467,134
SUMMARY OF OPERATIONS:
Total Revenues	186,637	$ 179,915	376,187	$ 373,813
Net Income (Loss)	28,153	$ 23,101	57,263	198,044
Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	584,917		584,917		590,853
Total Debt	290,912		290,912		230,305
Total Equity (Deficit)	190,862		190,862		244,186
Company’s Investment	77,915		77,915		107,192
SUMMARY OF OPERATIONS:
Total Revenues			33,408	31,995
Net Income (Loss)			7,898	9,276
Company's Share of Income (Loss)			3,698	5,140
DC Charlotte Plaza LLLP | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	170,290		170,290		173,704
Total Debt	0		0		0
Total Equity (Deficit)	90,666		90,666		90,648
Company’s Investment	47,000		47,000		47,941
SUMMARY OF OPERATIONS:
Total Revenues			10,218	10,429
Net Income (Loss)			3,679	3,681
Company's Share of Income (Loss)			1,712	1,661
Austin 300 Colorado Project, LP | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	168,168		168,168		165,586
Total Debt	91,716		91,716		86,848
Total Equity (Deficit)	68,825		68,825		68,567
Company’s Investment	39,121		39,121		38,488
SUMMARY OF OPERATIONS:
Total Revenues			3,350	195
Net Income (Loss)			258	95
Company's Share of Income (Loss)			109	48
AMCO 120 WT Holdings, LLC | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	84,876		84,876		85,449
Total Debt	0		0		0
Total Equity (Deficit)	84,233		84,233		84,311
Company’s Investment	15,712		15,712		15,735
SUMMARY OF OPERATIONS:
Total Revenues			4,140	584
Net Income (Loss)			(116)	(1,310)
Company's Share of Income (Loss)			(29)	(272)
HICO Victory Center LP | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	16,120		16,120		16,544
Total Debt	0		0		0
Total Equity (Deficit)	15,895		15,895		15,709
Company’s Investment	10,681		10,681		10,595
SUMMARY OF OPERATIONS:
Total Revenues			164	197
Net Income (Loss)			164	197
Company's Share of Income (Loss)			84	98
Charlotte Gateway Village, LLC | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF OPERATIONS:
Total Revenues			378	6,684
Net Income (Loss)			373	3,400
Company's Share of Income (Loss)			186	1,699
Carolina Square Holdings LP | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	118,521		118,521		118,616
Total Debt	133,774		133,774		77,034
Total Equity (Deficit)	(28,799)		(28,799)		21,888
Company’s Investment	(15,487)		(15,487)		12,430
SUMMARY OF OPERATIONS:
Total Revenues			8,789	7,209
Net Income (Loss)			1,518	1,228
Company's Share of Income (Loss)			704	569
Crawford Long - CPI, LLC | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	26,672		26,672		29,641
Total Debt	65,422		65,422		66,423
Total Equity (Deficit)	(40,225)		(40,225)		(38,253)
Company’s Investment	(19,316)		(19,316)		(18,289)
SUMMARY OF OPERATIONS:
Total Revenues			6,369	6,453
Net Income (Loss)			2,028	1,787
Company's Share of Income (Loss)			935	852
Other | Equity Method Investment, Nonconsolidated Investee or Group of Investees
SUMMARY OF FINANCIAL POSITION:
Total Assets	270		270		1,313
Total Debt	0		0		0
Total Equity (Deficit)	267		267		1,316
Company’s Investment	$ 204		204		$ 292
SUMMARY OF OPERATIONS:
Total Revenues			0	244
Net Income (Loss)			(6)	198
Company's Share of Income (Loss)			$ (3)	$ 485