Consolidated Statements Of Equity And Redeemable Noncontrolling Interests - USD ($) $ in Thousands	Total	Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]
Net income attributable to noncontrollling interests					$ 1,066
Net income attributable to noncontrolling interests						$ 151
Beginning Balance (in shares) at Dec. 31, 2012		59,812,796
Issuance of common stock through equity compensation plans (in shares)		58,002
Issuance of common stock through Employee Investment Plan (401-K), (in shares)		42,073
Issuance of common stock through Dividend Reinvestment Plan, (in shares)		163,881
Stock Issued During Period, Shares, Acquisitions	0
Beginning Balance at Dec. 31, 2012		$ 889,237	$ (6,700)	$ 376,940	17,658	4,938
Equity compensation expense		6,002
Issuance of common stock through equity compensation plans		(1,342)
Issuance of common stock through Employee Investment Plan (401-K)		1,127
Issuance of common stock through Dividend Reinvestment Plan		4,360
Stock Issued During Period, Value, Acquisitions Net of Issuance Costs	$ 0
Adjustments Related to Tax Withholding for Share-based Compensation		0
Stock Repurchased During Period, Value		0		0
Equity transactions of consolidated subsidiaries		(3,007)
Other comprehensive income (loss)	881		881
Supplemental pro forma AERC net income (1)	111,077			111,077
Cash dividends paid (common stock)				(73,276)
Issuance of subsidiary noncontrolling interests					480
Other					4,979
Purchase of subsidiary noncontrolling interests					(4,182)	(405)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	0
Valuation adjustments and other noncontrolling interests activity				7,649		(11,205)
Ending Balance at Dec. 31, 2013	1,298,266	$ 896,993	(5,819)	407,092	20,001	15,889
Ending Balance (in shares) at Dec. 31, 2013		60,076,752
Stock Repurchased During Period, Shares		0
Payments for Repurchase of Redeemable Noncontrolling Interest	0	$ 0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation		$ 616
Total equity	$ 1,318,267
Net income attributable to noncontrollling interests					240
Net income attributable to noncontrolling interests						(4)
Issuance of common stock through equity compensation plans (in shares)		51,127
Issuance of common stock through Employee Investment Plan (401-K), (in shares)		33,168
Issuance of common stock through Dividend Reinvestment Plan, (in shares)		110,501
Stock Issued During Period, Shares, Acquisitions	4,501,441
Equity compensation expense		$ 7,676
Issuance of common stock through equity compensation plans		108
Issuance of common stock through Employee Investment Plan (401-K)		1,005
Issuance of common stock through Dividend Reinvestment Plan		3,441
Stock Issued During Period, Value, Acquisitions Net of Issuance Costs	$ 149,625
Adjustments Related to Tax Withholding for Share-based Compensation		0
Stock Repurchased During Period, Value		(40,486)		(39,370)
Equity transactions of consolidated subsidiaries		(1,062)
Other comprehensive income (loss)	(2,069)		(2,069)
Supplemental pro forma AERC net income (1)	192,041			192,041
Cash dividends paid (common stock)				(78,314)
Issuance of subsidiary noncontrolling interests					0
Other					2,942
Purchase of subsidiary noncontrolling interests					0	(12)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(23,612)
Valuation adjustments and other noncontrolling interests activity				(10,150)		15,873
Ending Balance at Dec. 31, 2014	$ 1,483,671	$ 999,960	(7,888)	491,599	(429)	0
Ending Balance (in shares) at Dec. 31, 2014	62,243,374	62,243,374
Stock Repurchased During Period, Shares		(2,529,615)
Payments for Repurchase of Redeemable Noncontrolling Interest	$ (20,871)	$ (20,871)
Excess Tax Benefit from Share-based Compensation, Financing Activities		$ 3,531
Total equity	$ 1,483,242
Net income attributable to noncontrollling interests					90
Net income attributable to noncontrolling interests						0
Issuance of common stock through equity compensation plans (in shares)		125,620
Issuance of common stock through Employee Investment Plan (401-K), (in shares)		33,057
Issuance of common stock through Dividend Reinvestment Plan, (in shares)		0
Stock Issued During Period, Shares, Acquisitions	0
Equity compensation expense		$ 6,035
Issuance of common stock through equity compensation plans		462
Issuance of common stock through Employee Investment Plan (401-K)		1,099
Issuance of common stock through Dividend Reinvestment Plan		0
Stock Issued During Period, Value, Acquisitions Net of Issuance Costs	$ 0
Adjustments Related to Tax Withholding for Share-based Compensation		(1,832)
Stock Repurchased During Period, Value		(1,431)		(1,489)
Equity transactions of consolidated subsidiaries		0
Other comprehensive income (loss)	1,238		1,238
Supplemental pro forma AERC net income (1)	123,227			123,227
Cash dividends paid (common stock)				(82,397)
Issuance of subsidiary noncontrolling interests					0
Other					0
Purchase of subsidiary noncontrolling interests					0	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	0
Valuation adjustments and other noncontrolling interests activity				0		0
Ending Balance at Dec. 31, 2015	$ 1,528,626	$ 1,004,336	$ (6,650)	$ 530,940	$ (339)	$ 0
Ending Balance (in shares) at Dec. 31, 2015	62,312,651	62,312,651
Stock Repurchased During Period, Shares		(89,400)
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 0	$ 0
Excess Tax Benefit from Share-based Compensation, Financing Activities		$ 43
Total equity	$ 1,528,287