QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 62,903	$ 63,013	$ 59,239	$ 56,384	$ 56,931	$ 48,459	$ 45,112	$ 36,822	$ 241,539	$ 187,325	$ 121,578
Net interest income after provision for loan losses	33,297	33,328	31,602	29,409	30,728	28,381	28,211	21,831	127,636	109,151	72,233
Other income	72,183	7,549	86,452	35,037	31,906	61,337	55,489	40,434	201,221	189,166	241,705
Costs and expenses	38,347	42,260	44,180	43,379	48,045	42,207	45,258	38,575	168,166	174,086	121,475
Income (loss) before taxes	67,133	(1,383)	73,874	21,067	14,589	47,511	38,442	23,690	160,691	124,231	192,463
Income tax expense (benefit)	10,457	(4,181)	5,177	3,104	2,783	10,335	8,199	5,289	14,557	26,605	3,730
Net income	56,676	2,798	68,697	17,963	11,806	37,176	30,243	18,401	146,134	97,626	188,733
Net (income) loss attributable to noncontrolling interest in consolidated joint ventures	(2,146)	85	684	(191)	(83)	306	(46)	192	(1,568)	370	1,098
Net (income) loss attributable to predecessor unitholders					0	0	0	12,628	0	12,628	189,831
Net (income) loss attributable to noncontrolling interest in operating partnership	(27,407)	430	(35,171)	(8,597)	(7,350)	(22,827)	(17,691)	(18,568)	(70,745)	(66,437)	$ 189,831
Net income attributable to Class A common shareholders	$ 27,123	$ 3,313	$ 34,210	$ 9,175	$ 4,374	$ 14,656	$ 12,505	$ 12,652	$ 73,821	$ 44,187
Basic (in dollars per share)	$ 0.51	$ 0.06	$ 0.68	$ 0.18	$ 0.09	$ 0.30	$ 0.26	$ 0.26	$ 1.43	$ 0.90
Diluted (in dollars per share)	0.50	0.06	0.67	0.15	$ 0.09	$ 0.28	$ 0.22	$ 0.24	$ 1.42	$ 0.86
Dividends per share of common stock (in dollars per share)	$ 1.45	$ 0.275	$ 0.25	$ 0.25