Investment in Unconsolidated Joint Ventures (MSREF/Cousins Terminus 200 LLC) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Variable rate basis	LIBOR
Basis spread on variable rate (percent)	1.50%
MSREF Terminus Two Hundred LLC [Member]
Schedule of Equity Method Investments [Line Items]
Square footage of real estate property (square feet)	566,000
Ownership percentage equity method investment (percent)	20.00%
Decreased amount available under construction loan	92,000,000
Basis spread on variable rate (percent)	2.50%
Cash balance of joint venture	684,000
LIBOR [Member]
Schedule of Equity Method Investments [Line Items]
Variable rate basis	LIBOR
Basis spread on variable rate (percent)	1.00%
LIBOR [Member] | MSREF Terminus Two Hundred LLC [Member]
Schedule of Equity Method Investments [Line Items]
Variable rate basis	LIBOR
Morgan Stanley [Member] | MSREF Terminus Two Hundred LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage equity method investment (percent)	80.00%