Property Transactions (Textual) (Details) (USD $)	12 Months Ended							12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Third party management and leasing business [Member]	Dec. 31, 2012 Third party management and leasing business [Member]	Dec. 31, 2011 Third party management and leasing business [Member]	Dec. 31, 2012 MSREF Terminus Two Hundred LLC [Member] sqft	Dec. 31, 2013 2100 Ross Avenue [Member] sqft	Dec. 31, 2012 2100 Ross Avenue [Member]	Dec. 31, 2011 Promenade Atlanta, GA [Member]	Dec. 31, 2012 Promenade Atlanta, GA [Member] sqft	Feb. 28, 2013 Terminus Two Hundred LLC [Member] MSREF Terminus Two Hundred LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of discontinued investment properties	$ 11,489,000	$ 18,407,000	$ 8,519,000	$ 4,577,000	$ 7,459,000	$ 0
Square footage of real estate property (square feet)							566,000	844,000			777,000
Purchase price of building									59,200,000	134,700,000
Liabilities assumed								4,200,000
Acquisition costs related to purchase								408,000			292,000
Distributions from Unconsolidated Joint Ventures	88,635,000	67,435,000	8,428,000
Ownership Percentage of Partner in Joint Venture												80.00%
Proceeds from investment property sales	$ 178,966,000	$ 273,386,000	$ 143,623,000