ORGANIZATION AND BASIS OF PRESENTATION - Summary of General Terms and Operating Partnership's Equity Interests (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2013
Fund II
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Payments of dividends			$ 47.1
Operating Partnership | Fund I and Mervyns I
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating Partnership Share of Capital	[1]	22.22%
Fund Size	[1]	$ 90.0
Capital Called	[1],[2]	86.6
Unfunded Commitment	[1]	$ 0.0
Equity Interest Held By Operating Partnership	[1]	37.78%
Preferred Return	[1]	9.00%
Capital Returned	[1],[2]	$ 194.4
Operating Partnership | Fund II and Mervyns II
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating Partnership Share of Capital	[3]	20.00%
Fund Size	[3]	$ 300.0
Capital Called	[2],[3]	300.0
Unfunded Commitment	[3]	$ 47.1
Equity Interest Held By Operating Partnership	[3]	20.00%
Preferred Return	[3]	8.00%
Capital Returned	[2],[3]	$ 131.6
Operating Partnership | Fund III
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating Partnership Share of Capital		19.90%
Fund Size	[3]	$ 502.5
Capital Called	[2]	381.6
Unfunded Commitment		$ 68.4
Equity Interest Held By Operating Partnership		19.90%
Preferred Return		6.00%
Capital Returned	[2]	$ 429.1
Operating Partnership | Fund IV
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating Partnership Share of Capital		23.12%
Fund Size	[3]	$ 540.6
Capital Called	[2]	179.4
Unfunded Commitment		$ 361.2
Equity Interest Held By Operating Partnership		23.12%
Preferred Return		6.00%
Capital Returned	[2]	$ 101.9

[1] Fund I and Mervyns I have returned all capital and preferred return. The Operating Partnership is now entitled to a Promote on all future cash distributions.

[2] Represents the total for the Funds, including the Operating Partnership and noncontrolling interests' shares.

[3] During 2013, a distribution of $47.1 million was made to the Fund II investors, including the Operating Partnership. This amount is subject to recontribution to Fund II until December 2016, if needed to fund the on-going development and construction of existing projects.