Investment in Unconsolidated Joint Ventures (Summary of Financial Data and Principal Activities) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Fees Earned from Unconsolidated Joint Ventures	$ 5,200,000		$ 7,800,000		$ 8,700,000
Document Fiscal Year Focus	2014		2013		2012
SUMMARY OF FINANCIAL POSITION:
Total Assets	618,580,000		657,384,000
Total Debt	394,934,000		428,153,000
Total Equity	202,597,000		210,460,000
Company's Investment	77,461,000		84,322,000
SUMMARY OF OPERATIONS:
Total Revenues	109,326,000		137,107,000		148,338,000
Net Income (Loss)	25,357,000		72,894,000		52,638,000
Company's Share of Income (Loss)	11,268,000		67,325,000		39,258,000
Terminus Office Holdings [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	288,415,000		297,815,000
Total Debt	213,640,000		215,942,000
Total Equity	62,830,000		69,867,000
Company's Investment	32,323,000		35,885,000
SUMMARY OF OPERATIONS:
Total Revenues	39,531,000		33,109,000		0
Net Income (Loss)	663,000		(408,000)		0
Company's Share of Income (Loss)	308,000		(182,000)		0
EP I LLC [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	85,228,000		88,130,000
Total Debt	58,029,000		57,092,000
Total Equity	26,671,000		29,229,000
Company's Investment	22,905,000		25,319,000
SUMMARY OF OPERATIONS:
Total Revenues	12,049,000		8,261,000		796,000
Net Income (Loss)	2,583,000		100,000		(441,000)
Company's Share of Income (Loss)	1,937,000		75,000		(330,000)
Cousins Watkins LLC [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	0		51,653,000
Total Debt	0		27,710,000
Total Equity	0		23,081,000
Company's Investment	0		17,213,000
SUMMARY OF OPERATIONS:
Total Revenues	4,415,000		5,483,000		5,575,000
Net Income (Loss)	8,286,000		55,000		(24,000)
Company's Share of Income (Loss)	4,168,000		2,306,000		2,397,000
Charlotte Gateway Village, LLC [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	130,272,000		135,966,000
Total Debt	35,530,000		52,408,000
Total Equity	92,808,000		82,373,000
Company's Investment	11,218,000		11,252,000
SUMMARY OF OPERATIONS:
Total Revenues	33,903,000		33,281,000		32,901,000
Net Income (Loss)	11,645,000		10,693,000		9,704,000
Company's Share of Income (Loss)	1,176,000		1,176,000		1,176,000
HICO Victory Center LP [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	9,962,000		0
Total Debt	0		0
Total Equity	9,962,000		0
Company's Investment	7,572,000		0
SUMMARY OF OPERATIONS:
Total Revenues	0		0		0
Net Income (Loss)	0		0		0
Company's Share of Income (Loss)	0		0		0
EP II LLC [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	42,772,000		12,644,000
Total Debt	12,735,000		1,000
Total Equity	24,969,000		11,695,000
Company's Investment	19,905,000		9,566,000
SUMMARY OF OPERATIONS:
Total Revenues	0		0		0
Net Income (Loss)	0		0		0
Company's Share of Income (Loss)	0		0		0
Temco Associates
SUMMARY OF FINANCIAL POSITION:
Total Assets	6,910,000		8,474,000
Total Debt	0		0
Total Equity	6,709,000		8,315,000
Company's Investment	3,027,000		4,083,000
SUMMARY OF OPERATIONS:
Total Revenues	2,155,000		630,000		702,000
Net Income (Loss)	495,000		96,000		(65,000)
Company's Share of Income (Loss)	(6,000)		(12,000)		(236,000)
CL Realty, L.L.C. [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	7,264,000		7,602,000
Total Debt	0		0
Total Equity	7,042,000		7,374,000
Company's Investment	3,546,000		3,704,000
SUMMARY OF OPERATIONS:
Total Revenues	1,573,000		1,603,000		2,667,000
Net Income (Loss)	1,069,000		1,027,000		1,068,000
Company's Share of Income (Loss)	542,000		524,000		221,000
MSREF/Cousins Terminus 200 LLC [Member]
SUMMARY OF OPERATIONS:
Total Revenues	(19,000)		1,197,000		12,265,000
Net Income (Loss)	14,000		(235,000)		(1,069,000)
Company's Share of Income (Loss)	3,000		(69,000)		(215,000)
Cp Venture Five LLC [Member]
SUMMARY OF OPERATIONS:
Total Revenues	0		20,192,000		30,007,000
Net Income (Loss)	0		3,075,000		3,943,000
Company's Share of Income (Loss)	(17,000)		17,070,000		1,059,000
CP Venture Two LLC [Member]
SUMMARY OF OPERATIONS:
Total Revenues	0		12,965,000		19,533,000
Net Income (Loss)	0		7,033,000		10,473,000
Company's Share of Income (Loss)	0		21,590,000		1,208,000
Palisades West LLC [Member]
SUMMARY OF OPERATIONS:
Total Revenues	0		0		15,401,000
Net Income (Loss)	0		(27,000)		5,330,000
Company's Share of Income (Loss)	0		0		25,547,000
Ten Peachtree Place Associates [Member]
SUMMARY OF OPERATIONS:
Total Revenues	0		0		2,488,000
Net Income (Loss)	0		0		20,895,000
Company's Share of Income (Loss)	0		0		7,843,000
CF Murfreesboro Associates [Member]
SUMMARY OF OPERATIONS:
Total Revenues	4,000		8,067,000		13,152,000
Net Income (Loss)	4,000		48,953,000		602,000
Company's Share of Income (Loss)	(390,000)		23,553,000		16,000
Wildwood Associates [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	16,400,000		21,127,000
Total Debt	0		0
Total Equity	16,389,000		21,121,000
Company's Investment	(1,106,000)	[1]	(1,689,000)	[1]
SUMMARY OF OPERATIONS:
Total Revenues	3,329,000		0		1,000
Net Income (Loss)	(1,704,000)		(151,000)		(139,000)
Company's Share of Income (Loss)	2,097,000		(75,000)		(70,000)
Crawford Long CPI LLC [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	29,946,000		32,042,000
Total Debt	75,000,000		75,000,000
Total Equity	(45,762,000)		(44,295,000)
Company's Investment	(21,931,000)	[1]	(21,071,000)	[1]
SUMMARY OF OPERATIONS:
Total Revenues	11,945,000		11,829,000		11,579,000
Net Income (Loss)	2,775,000		2,827,000		2,508,000
Company's Share of Income (Loss)	1,407,000		1,372,000		1,248,000
Other [Member]
SUMMARY OF FINANCIAL POSITION:
Total Assets	1,411,000		1,931,000
Total Debt	0		0
Total Equity	979,000		1,700,000
Company's Investment	2,000		60,000
SUMMARY OF OPERATIONS:
Total Revenues	441,000		490,000		1,271,000
Net Income (Loss)	(473,000)		(144,000)		(147,000)
Company's Share of Income (Loss)	$ 43,000		$ (3,000)		$ (606,000)

[1] Negative balances are included in deferred income on the balance sheets.