SEGMENT INFORMATION (Segment Information, by Segment) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013 sqft office	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 segment sqft office	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of operating segments									2
Average ownership interest in investments									40.00%
Area of real estate property	68,000,000								68,000,000
Number of offices	24								24
Management fees and commissions									$ 22,100,000	$ 20,800,000	$ 18,400,000
Management fees and commissions - related party									46,000,000	32,500,000	38,700,000
Rental and other income									43,000,000	8,500,000	5,100,000
Sale of real estate									10,100,000	2,300,000	400,000
Total revenue	29,600,000	33,200,000	36,000,000	22,400,000	23,000,000	15,200,000	14,100,000	11,800,000	121,200,000	64,100,000	62,600,000
Operating expenses									131,700,000	86,600,000	63,300,000
Depreciation and amortization									17,400,000	4,900,000	2,800,000
Total operating expenses	44,000,000	37,300,000	40,100,000	27,600,000	36,900,000	20,800,000	18,400,000	15,400,000	149,100,000	91,500,000	66,100,000
Equity in joint venture income									29,800,000	21,500,000	12,500,000
Interest income from loan pool participations and notes receivable	3,300,000	4,000,000	3,300,000	2,900,000	2,100,000	3,700,000	2,900,000	500,000	13,500,000	9,200,000	8,000,000
Operating income	(2,300,000)	9,300,000	11,100,000	(2,600,000)	(2,700,000)	(100,000)	3,700,000	2,400,000	15,400,000	3,300,000	17,000,000
Other Nonoperating Income (Expense) Including Discontinued Operations									(3,500,000)	6,300,000	2,800,000
Interest income									300,000	100,000	400,000
Interest income—related party									300,000	2,800,000	2,000,000
Acquisition related gains									56,600,000	25,500,000	6,300,000
Interest expense - consolidated property level debt									(39,900,000)	(26,100,000)	(19,000,000)
Interest expense - property level debt									(11,800,000)	(2,500,000)	(1,600,000)
Income (Loss) Before Income Taxes									16,800,000	6,500,000	5,500,000
Income from continuing operations before benefit from (provision for) income taxes	24,900,000	(2,000,000)	(1,800,000)	(4,500,000)	15,200,000	(6,600,000)	(2,100,000)	200,000	16,500,000	6,700,000	5,100,000
(Provision for) benefit from income taxes	(4,300,000)	(800,000)	500,000	1,700,000	(4,900,000)	2,500,000	1,100,000	1,500,000	(2,900,000)	200,000	2,000,000
Net income	20,600,000	(2,700,000)	(1,300,000)	(2,600,000)	10,300,000	(4,100,000)	(1,000,000)	1,500,000	13,900,000	6,700,000	7,500,000
Assets	1,798,800,000				1,283,800,000				1,798,800,000	1,283,800,000
Expenditures for long lived assets									168,500,000	119,000,000	2,700,000
Investments [Member]
Segment Reporting Information [Line Items]
Rental and other income									43,000,000	8,500,000	5,100,000
Sale of real estate									10,100,000	2,300,000	400,000
Total revenue									53,100,000	10,800,000	5,500,000
Operating expenses									69,100,000	36,900,000	19,300,000
Depreciation and amortization									15,600,000	4,400,000	2,400,000
Total operating expenses									84,700,000	41,300,000	21,700,000
Equity in joint venture income									29,800,000	21,500,000	12,500,000
Interest income from loan pool participations and notes receivable									13,500,000	9,200,000	8,000,000
Operating income									11,700,000	200,000	4,300,000
Interest income—related party									(3,800,000)	6,300,000	2,400,000
Acquisition related gains									56,600,000	25,500,000	6,300,000
Interest expense - consolidated property level debt									(11,800,000)	(2,500,000)	(1,600,000)
Income from continuing operations before benefit from (provision for) income taxes									52,700,000	29,500,000	11,400,000
Assets	1,537,400,000				1,070,600,000				1,537,400,000	1,070,600,000
Expenditures for long lived assets									168,500,000	119,000,000	2,700,000
Services [Member]
Segment Reporting Information [Line Items]
Management fees and commissions									22,100,000	20,800,000	18,400,000
Management fees and commissions - related party									46,000,000	32,500,000	38,700,000
Total revenue									68,100,000	53,300,000	57,100,000
Operating expenses									40,700,000	33,100,000	31,400,000
Depreciation and amortization									1,300,000	200,000	100,000
Total operating expenses									42,000,000	33,300,000	31,500,000
Operating income									26,100,000	20,000,000	25,600,000
Income from continuing operations before benefit from (provision for) income taxes									26,100,000	20,000,000	25,600,000
Assets	132,600,000				105,400,000				132,600,000	105,400,000
Corporate [Member]
Segment Reporting Information [Line Items]
Rental and other income
Total revenue
Operating expenses									21,900,000	16,700,000	12,600,000
Depreciation and amortization									500,000	300,000	200,000
Total operating expenses									22,400,000	17,000,000	12,800,000
Operating income									(22,400,000)	(17,000,000)	(12,800,000)
Interest income									300,000	200,000	300,000
Interest expense - consolidated property level debt									(39,900,000)	(26,100,000)	(19,000,000)
Income from continuing operations before benefit from (provision for) income taxes									(62,000,000)	(42,900,000)	(31,500,000)
(Provision for) benefit from income taxes									(2,900,000)	200,000	2,000,000
Net income									(64,900,000)	(42,700,000)	(29,500,000)
Assets	$ 128,800,000				$ 107,800,000				$ 128,800,000	$ 107,800,000