Summary Of Significant Accounting Policies Consolidated Statement of Cash Flows - Supplemental Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Total interest costs incurred			$ 97,074	$ 96,903
Interest capitalized			(14,507)	(14,787)
Interest expense	$ 27,052	$ 28,166	82,567	82,116
Cash paid for interest, net of amounts capitalized			82,118	85,614
Cash paid for income taxes			450	699
Mortgage loans assumed with acquisition			16,951	0
DownREIT operating partnership units redeemed for common shares			11,935	101
Shares issued under dividend reinvestment plan			$ 1,337	$ 1,431