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					$ 240
Net income attributable to noncontrolling interests						$ (4)
Beginning Balance (in shares) at Dec. 31, 2013		60,076,752
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
Shares Issued Under Sales Agency Agreements		0
Stock Issued During Period, Shares, Acquisitions		4,501,441
Beginning Balance at Dec. 31, 2013		$ 896,993	$ (5,819)	$ 407,092	20,001	15,889
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
Shares Issued Under Sales Agency Agreements		0
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)
Other					2,942
Purchase of subsidiary noncontrolling interests						(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
Stock Repurchased During Period, Shares		(2,529,615)
Payments for Repurchase of Redeemable Noncontrolling Interest	(20,871)	$ (20,871)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net		$ 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
Shares Issued Under Sales Agency Agreements		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
Shares Issued Under Sales Agency Agreements		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)
Other					0
Purchase of subsidiary noncontrolling interests						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
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net		$ 43
Total equity	1,528,287
Net income attributable to noncontrollling interests					88
Net income attributable to noncontrolling interests						0
Issuance of common stock through equity compensation plans (in shares)		203,727
Issuance of common stock through Employee Investment Plan (401-K), (in shares)		26,556
Issuance of common stock through Dividend Reinvestment Plan, (in shares)		0
Shares Issued Under Sales Agency Agreements		1,645,000
Stock Issued During Period, Shares, Acquisitions		0
Equity compensation expense		$ 7,065
Issuance of common stock through equity compensation plans		624
Issuance of common stock through Employee Investment Plan (401-K)		1,061
Issuance of common stock through Dividend Reinvestment Plan		0
Shares Issued Under Sales Agency Agreements		65,267
Stock Issued During Period, Value, Acquisitions Net of Issuance Costs	0
Adjustments Related to Tax Withholding for Share-based Compensation		(3,072)
Stock Repurchased During Period, Value		0		0
Equity transactions of consolidated subsidiaries		0
Other comprehensive income (loss)	(918)		(918)
Supplemental pro forma AERC net income (1)	137,228			137,228
Cash dividends paid (common stock)				(87,154)
Other					0
Purchase of subsidiary noncontrolling interests						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, 2016	$ 1,648,727	$ 1,075,281	$ (7,568)	$ 581,014	$ (251)	$ 0
Ending Balance (in shares) at Dec. 31, 2016	64,187,934	64,187,934
Stock Repurchased During Period, Shares		0
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 0	$ 0
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net		$ 0
Total equity	$ 1,648,476