CONSOLIDATED STATEMENTS OF CASH FLOWS (UNITED DOMINION REALTY, L.P.) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Activities
Net income/(loss)	$ 221,542	$ 132,655	$ 320,380
Adjustments to reconcile net income/(loss) to net cash provided by/(used in) operating activities:
Depreciation and amortization	435,679	436,462	425,638
(Gain)/loss on sale of real estate owned	(136,197)	(43,404)	(226,199)
(Income)/loss from unconsolidated entities	5,055	(31,257)	(52,234)
Other	4,998	20,467	39,490
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	(13,880)	(9,008)	(29,399)
Increase/(decrease) in operating liabilities	24,987	(4,278)	(12,084)
Net cash provided by/(used in) operating activities	560,676	518,915	536,568
Investing Activities
Acquisition of real estate assets		(96,791)	(163,015)
Proceeds from sales of real estate investments, net	247,031	71,235	301,799
Capital expenditures and other major improvements — real estate assets, net of escrow reimbursement	(112,359)	(124,728)	(91,740)
Distributions received from unconsolidated entities	42,683	116,329	66,116
Net cash provided by/(used in) investing activities	(113,548)	(407,406)	(112,720)
Financing Activities
Payments on secured debt	(279,243)	(326,346)	(375,308)
Other	(41,485)	(21,361)	(11,154)
Net cash provided by/(used in) financing activities	(260,067)	(111,785)	(429,282)
Net increase/(decrease) in cash, cash equivalents, and restricted cash	187,061	(276)	(5,434)
Cash, cash equivalents, and restricted cash, beginning of year	21,830	22,106	27,540
Cash, cash equivalents, and restricted cash, end of year	208,891	21,830	22,106
Supplemental Information:
Interest paid during the period, net of amounts capitalized	132,466	126,348	124,635
Non-cash transactions:
Development costs and capital expenditures incurred but not yet paid	10,304	43,930	46,285
Distributions declared but not yet paid	97,666	91,455	86,936
United Dominion Reality L.P.
Operating Activities
Net income/(loss)	231,485	107,855	79,262
Adjustments to reconcile net income/(loss) to net cash provided by/(used in) operating activities:
Depreciation and amortization	143,481	152,473	147,074
(Gain)/loss on sale of real estate owned	(75,507)	(41,272)	(33,180)
(Income)/loss from unconsolidated entities	(43,496)	19,256	37,425
Other	1,771	5,642	1,769
Changes in operating assets and liabilities:
(Increase)/decrease in operating assets	(3,260)	(3,992)	(3,251)
Increase/(decrease) in operating liabilities	1,194	(4,705)	(158)
Net cash provided by/(used in) operating activities	255,668	235,257	228,941
Investing Activities
Acquisition of real estate assets		(137,332)
Proceeds from sales of real estate investments, net	98,533	67,985	44,553
Capital expenditures and other major improvements — real estate assets, net of escrow reimbursement	(44,227)	(53,346)	(69,902)
Distributions received from unconsolidated entities	17,377	16,704	15,894
Net cash provided by/(used in) investing activities	71,683	(105,989)	(9,455)
Financing Activities
Advances (to)/from the General Partner, net	(348,381)	163,196	(180,391)
Payments on secured debt	(133,205)	(275,345)	(30,322)
Issuance of notes payable to the General Partner	169,577
Distributions paid to partnership unitholders	(12,705)	(11,694)	(10,770)
Other	(1,821)	(5,003)
Net cash provided by/(used in) financing activities	(326,535)	(128,846)	(221,483)
Net increase/(decrease) in cash, cash equivalents, and restricted cash	816	422	(1,997)
Cash, cash equivalents, and restricted cash, beginning of year	12,872	12,450	14,447
Cash, cash equivalents, and restricted cash, end of year	13,688	12,872	12,450
Supplemental Information:
Interest paid during the period, net of amounts capitalized	17,173	24,331	22,922
Non-cash transactions:
Reallocation of credit facilities debt from the General Partner			12,292
Development costs and capital expenditures incurred but not yet paid	2,056	2,032	5,098
LTIP Unit grants	15,839	7,763	3,735
Distributions declared but not yet paid	59,461	$ 57,025	$ 54,192
Conversion of Advances (to)/from the General Partner to notes payable	$ 257,204