SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2019 USD ($) home	Jan. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 31, 2020 USD ($)	Jan. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)
Accounting policies
Lease classification per practical expedient			true
Recognition of operating lease right-of-use assets			$ 204,225
Recognition of operating lease liabilities			198,558
Allocation of other comprehensive income/(loss)			(826)	$ 244
Significant Accounting Policies
Development costs excluding direct costs and capitalized interest			8,400	7,500	$ 8,800
Interest capitalized during period			5,100	10,600	18,600
Notes receivable			153,650	42,259
Promoted interest received			8,500	0	0
Interest Income, Related Party			0
Amortization schedule term	30 years
Note receivable interest income			$ 5,500	4,100	1,800
Minimum period units are outstanding prior to redemption (in years)			1 year
Current Income Tax Expense (Benefit)			$ 0
Deferred tax liabilities, net			(1,600)
Unrecognized tax benefit, accrued interest or penalties due to examination			0
Advertising expense			$ 6,500	6,700	6,200
Minimum percentage of carrying value of real estate portfolio			10.00%
Bellevue, WA 259 Home Community
Significant Accounting Policies
Aggregate commitment on note receivable			$ 115,000
Number of apartment homes | home	259
Deposit made under purchase option agreement			10,000
Payment to acquire real estate	$ 170,000
Purchase option exercisable term	30 days
Maturity date extension term	10 years
Loan interest term	3 years
Note due February 2020
Significant Accounting Policies
Notes receivable			$ 16,400	14,659
Note receivable interest rate			10.00%
Aggregate commitment on note receivable			$ 16,400
Additional amount loaned			1,700
Note maturity public capital threshold			5,000
Note due January 2023
Significant Accounting Policies
Notes receivable						$ 19,400
Note due March 2020
Significant Accounting Policies
Notes receivable			$ 20,000	20,000				$ 20,000
Note receivable interest rate			12.00%
Aggregate commitment on note receivable								$ 20,000
Note due October 2020
Significant Accounting Policies
Notes receivable			$ 2,250	2,000
Note receivable interest rate			8.00%
Aggregate commitment on note receivable			$ 2,300
Additional amount loaned			300
Note maturity public capital threshold			$ 10,000
Note due August 2022
Significant Accounting Policies
Notes receivable				5,600
Proceeds from secured notes receivable		$ 5,600
Procceds from accrued interest		200
Note receivable interest rate			10.00%
Promoted interest received		$ 8,500
Note due October 2022
Significant Accounting Policies
Notes receivable			$ 115,000
Note receivable interest rate			4.75%
Minimum
Significant Accounting Policies
Ownership (as a percent)			100.00%
Minimum | Buildings
Significant Accounting Policies
Estimated useful lives			30 years
Minimum | Building improvements
Significant Accounting Policies
Estimated useful lives			10 years
Minimum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies
Estimated useful lives			3 years
Maximum
Significant Accounting Policies
Deferred tax liabilities, net				(100)
Maximum | Buildings
Significant Accounting Policies
Estimated useful lives			55 years
Maximum | Building improvements
Significant Accounting Policies
Estimated useful lives			35 years
Maximum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies
Estimated useful lives			10 years
Adjustment | ASU 2016-02
Accounting policies
Recognition of operating lease right-of-use assets							$ 94,300
Recognition of operating lease liabilities							88,300
Prepaid rent and intangible assets							$ 6,000
Noncontrolling Interests
Accounting policies
Allocation of other comprehensive income/(loss)			$ (800)	$ 200	$ 300