Summary Of Significant Accounting Policies - Schedule of Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
SUPPLEMENTAL DISCLOSURES:
Total interest costs incurred			$ 57,156		$ 57,364
Interest capitalized			(9,543)		(11,014)
Interest expense	$ 23,445	$ 23,213	47,613		46,350
Cash paid for interest, net of amounts capitalized			71,832	[1]	40,885
Cash paid for income taxes			222		309
NON-CASH INVESTING AND FINANCING TRANSACTIONS:
Mortgage loans assumed with acquisition			18,666		68,282
DownREIT operating partnership units issued with acquisition			7,742		65,348
Mortgage loan refinanced			0		11,500
Repayment of note payable with public funding/related construction-in-progress offset			0		10,000
Shares issued under dividend reinvestment plan			983		$ 900
Prepayment premium on senior note			$ 19,200

[1] 2015 includes $19.2 million related to early extinguishment of debt.