QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Additional return on equity from Company's investments									$ 1,017	$ 294	$ 1,957
Interest income	$ 60,721	$ 60,284	$ 55,766	$ 59,601	$ 62,903	$ 63,013	$ 59,239	$ 56,384	236,372	241,539	187,325
Net interest income after provision for loan losses	28,517	29,599	27,214	29,915	33,297	33,328	31,602	29,409	115,245	127,636	109,151
Other income (loss)	89,212	69,335	11,835	(7,070)	72,183	7,549	86,452	35,037			189,166
Costs and expenses	45,335	40,615	37,405	35,162	38,347	42,260	44,180	43,379	158,517	168,166	174,086
Income (loss) before taxes	72,394	58,319	1,644	(12,317)	67,133	(1,383)	73,874	21,067	120,040	160,691	124,231
Income tax expense (benefit)	773	8,721	(2,301)	(873)	10,457	(4,181)	5,177	3,104	6,320	14,557	26,605
Net income	71,621	49,598	3,945	(11,444)	56,676	2,798	68,697	17,963	113,720	146,134	97,626
Net (income) loss attributable to noncontrolling interest in consolidated joint ventures	(298)	439	(235)	232	(2,146)	85	684	(191)	138	(1,568)	370
Net (income) loss attributable to noncontrolling interest in operating partnership	(29,467)	(22,429)	(908)	5,673	(27,407)	430	(35,171)	(8,597)	(47,131)	(70,745)	(66,437)
Net income (loss) attributable to Class A common shareholders	$ 41,856	$ 27,608	$ 2,802	$ (5,539)	$ 27,123	$ 3,313	$ 34,210	$ 9,175	$ 66,727	$ 73,821	$ 44,187
Basic net income (loss) per share of Class A common stock (in dollars per share)	$ 0.64	$ 0.44	$ 0.05	$ (0.09)	$ 0.51	$ 0.06	$ 0.68	$ 0.18	$ 1.08	$ 1.43	$ 0.90
Diluted (in dollars per share)	0.63	0.44	0.05	(0.09)	0.50	0.06	0.67	0.15	$ 1.06	$ 1.42	$ 0.86
Dividends per share of common stock (in dollars per share)	$ 0.460	$ 0.275	$ 0.275	$ 0.275	$ 1.450	$ 0.275	$ 0.250	$ 0.250
Noncontrolling Interest in Consolidated Joint Ventures | Out-of-Period Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Additional return on equity from Company's investments				$ 900