Consolidated Statements of Income - USD ($) $ in Thousands																3 Months Ended								12 Months Ended
	Nov. 26, 2019	Aug. 22, 2019	May 30, 2019	May 01, 2019	Feb. 27, 2019	Feb. 06, 2019	Jan. 24, 2019	Oct. 30, 2018	Sep. 05, 2018	May 30, 2018	Feb. 27, 2018	Nov. 07, 2017	Sep. 01, 2017	Jun. 01, 2017	Mar. 01, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net interest income
Interest income																$ 76,196	$ 82,251	$ 85,322	$ 86,466	$ 90,994	$ 90,386	$ 85,230	$ 78,206	$ 330,235	$ 344,816	$ 263,667
Interest expense																								204,353	194,291	146,118
Net interest income																								125,882	150,525	117,549
Provision for loan losses																								2,600	13,900	0
Net interest income after provision for loan losses																24,857	30,854	32,653	34,918	41,009	28,610	36,513	30,493	123,282	136,625	117,549
Other income (loss)
Operating lease income				$ 3,900																				106,366
Operating lease income																									106,177	96,671
Sale of loans, net																								54,758	16,511	54,046
Realized gain (loss) on securities																								14,911	(5,808)	17,209
Unrealized gain (loss) on equity securities																								1,737	(1,605)	0
Unrealized gain (loss) on Agency interest-only securities																								84	555	1,405
Realized gain (loss) on sale of real estate, net																								1,392	95,881	11,423
Impairment of real estate																			(1,400)					(1,350)	0	0
Fee and other income																								24,403	26,285	18,341
Net result from derivative transactions																								(30,011)	15,926	(12,641)
Earnings (loss) from investment in unconsolidated joint ventures																								3,432	790	89
Gain (loss) on extinguishment/defeasance of debt						$ (1,100)																		(1,070)	(4,392)	(73)
Total other income (loss)																								174,652	250,320	186,470
Costs and expenses
Salaries and employee benefits																								67,768	60,117	70,463
Operating expenses																								22,595	21,696	21,421
Real estate operating expenses																								23,323	29,799	33,216
Fee expense																								6,090	5,055	4,996
Depreciation and amortization				$ 400																				38,511	41,959	40,332
Total costs and expenses																36,839	36,989	38,069	46,390	36,610	40,136	38,753	43,127	158,287	158,626	170,428
Income (loss) before taxes																47,619	32,060	38,291	21,677	27,810	84,668	44,141	71,700	139,647	228,319	133,591
Income tax expense (benefit)																2,169	1,112	2,219	(2,854)	964	1,204	573	3,902	2,646	6,643	7,712
Net income (loss)																45,450	30,948	36,072	24,531	26,846	83,464	43,568	67,798	137,001	221,676	125,879
Net (income) loss attributable to noncontrolling interest in consolidated joint ventures																4	(64)	307	447	268	(7,843)	133	(8,422)	694	(15,864)	(226)
Net (income) loss attributable to noncontrolling interest in operating partnership																$ (4,804)	$ (3,308)	$ (4,136)	$ (2,802)	$ (3,011)	$ (8,991)	$ (5,294)	$ (8,501)	$ (15,050)	$ (25,797)	$ (30,377)
Earnings per share:
Basic (in dollars per share)																$ 0.38	$ 0.26	$ 0.31	$ 0.21	$ 0.24	$ 0.69	$ 0.40	$ 0.53	$ 1.16	$ 1.85	$ 1.16
Diluted (in dollars per share)																$ 0.37	$ 0.26	$ 0.30	$ 0.21	$ 0.24	$ 0.67	$ 0.40	$ 0.53	$ 1.15	$ 1.84	$ 1.13
Weighted average shares outstanding:
Basic (in shares)																								105,455,849	97,226,027	81,902,524
Diluted (in shares)																								106,399,783	97,652,065	109,704,880
Class A Common Stock
Costs and expenses
Net income (loss) attributable to Class A common shareholders																$ 40,650	$ 27,577	$ 32,242	$ 22,175	$ 24,103	$ 66,630	$ 38,407	$ 50,875	$ 122,645	$ 180,015	$ 95,276
Earnings per share:
Basic (in dollars per share)																								$ 1.16	$ 1.85	$ 1.16
Diluted (in dollars per share)																								$ 1.15	$ 1.84	$ 1.13
Weighted average shares outstanding:
Basic (in shares)																								105,455,849	97,226,027	81,902,524
Diluted (in shares)																								106,399,783	97,652,065	109,704,880
Dividends per share of Class A common stock (in dollars per share)	$ 0.340	$ 0.340	$ 0.340		$ 0.340		$ 0.570	$ 0.570	$ 0.325	$ 0.325	$ 0.315	$ 0.315	$ 0.300	$ 0.300	$ 0.300	$ 0.340	$ 0.340	$ 0.340	$ 0.340	$ 0.570	$ 0.325	$ 0.325	$ 0.315	$ 1.360	$ 1.535	$ 1.215