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Investments in Equity Affiliates - All Investments (Details)	1 Months Ended	3 Months Ended			12 Months Ended
	Jan. 31, 2021	Dec. 31, 2021 USD ($) item	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2021 USD ($)
Investment in Equity Affiliates
Income from equity affiliates					$ 34,567,000	$ 76,161,000	$ 10,635,000
Indirect ownership percentage					9.20%
Noncontrolling interest invested					$ 48,071,000	892,000	13,522,000
Arbor Residential Investor LLC
Investment in Equity Affiliates
Income from equity affiliates					34,600,000	75,700,000		$ 7,200,000
Distribution received					28,000,000.0	43,200,000
Equity Investment									$ 9,600,000
Percentage of ownership interest of related party in the entity									50.00%
Arbor Residential Investor LLC \| Minimum
Investment in Equity Affiliates
Indirect ownership percentage	12.30%
Arbor Residential Investor LLC \| Maximum
Investment in Equity Affiliates
Indirect ownership percentage	16.30%
Arbor Residential Investor LLC \| Wakefield Investment Holdings Llc [Member]
Investment in Equity Affiliates
Percentage of ownership interest of related party in the entity									50.00%
Residential mortgage banking business
Investment in Equity Affiliates
Indirect ownership percentage									(65.00%)
AMAC Holdings III LLC
Investment in Equity Affiliates
Income from equity affiliates					1,300,000	900,000
Distribution received					3,800,000	100,000
Investment in real estate committed						$ 30,000,000.0
Investment in real estate		$ 20,300,000			20,300,000
Interest in a real estate investment (as a percent)						18.00%
Fifth Wall Ventures III
Investment in Equity Affiliates
Investment in real estate committed		25,000,000.0
Investment in real estate		5,400,000			$ 5,400,000
Interest in a real estate investment (as a percent)					7.60%
Number of investments					2
North Vermont Avenue
Investment in Equity Affiliates
Noncontrolling interest invested						$ 2,400,000
Noncontrolling interest in equity method investment (as a percent)						85.00%
Lightstone Value Plus REIT L.P.
Investment in Equity Affiliates
Equity Investment		$ 1,900,000			$ 1,900,000
West Shore Cafe
Investment in Equity Affiliates
Ownership percentage		50.00%			50.00%
Provided first mortgage loan to an affiliated entity					$ 1,700,000
Variable rate, spread (as a percent)					4.00%
Other-than-temporary impairment recorded							2,200,000
Provision for loan loss recorded							$ 1,700,000
JT Prime
Investment in Equity Affiliates
Equity Investment		$ 400,000			$ 400,000
Noncontrolling interest in equity method investment (as a percent)					50.00%
Century Summerfield Apartments
Investment in Equity Affiliates
Income from equity affiliates			$ 200,000
Distribution received			$ 17,200,000
Investment in real estate committed				$ 20,000,000.0
Investment in real estate				$ 17,000,000.0
Ownership percentage				50.00%
Tapestry on the River
Investment in Equity Affiliates
Income from equity affiliates		700,000
Distribution received		14,700,000
Investment in real estate										$ 14,000,000.0
Ownership percentage										48.90%
Emerson at Forney
Investment in Equity Affiliates
Income from equity affiliates		200,000
Distribution received		$ 3,200,000
Investment in real estate										$ 3,000,000.0
Ownership percentage										11.10%
Lexford Portfolio
Investment in Equity Affiliates
Distribution received					$ 1,100,000	$ 3,500,000
Noncontrolling interest					100,000
East River Portfolio
Investment in Equity Affiliates
Equity investment made					$ 100,000
Ownership percentage		5.00%			5.00%
Number of Real Estate Properties \| item		2			2
East River Portfolio \| Chief executive officer and other related parties
Investment in Equity Affiliates
Percentage of ownership interest of related party in the entity					95.00%