Quarterly Financial Information (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue as reported in Form 10-Qs	$ 49,070	$ 46,069	$ 43,484	$ 42,855	$ 42,795	$ 41,668	$ 37,914	$ 36,177	$ 181,479	$ 158,553	$ 149,623
Revenue of sold properties transferred to discontinued operations		(1,255)	(2,179)	(2,138)		(1,210)	(2,085)	(2,030)	(9,191)	(21,649)	(29,545)
Operating income	9,795	9,386	9,047	8,298	9,204	8,238	6,991	6,512	34,630	29,154	15,872
Net income	29,273	20,007	1,652	10,363	6,931	2,101	23,665	(2,086)	61,295	30,611	5,368
Net income attributable to AERC	29,273	19,993	1,638	10,346	6,911	2,093	23,669	(2,081)	61,250	30,592	5,328
Basic earnings per common share	$ 0.51	$ 0.40	$ 0.03	$ 0.21	$ 0.14	$ 0.04	$ 0.55	$ (0.05)	$ 1.18	$ 0.66	$ 0.13
Diluted earnings per common share	$ 0.51	$ 0.40	$ 0.03	$ 0.20	$ 0.14	$ 0.04	$ 0.54	$ (0.05)	$ 1.17	$ 0.66	$ 0.13
Scenario, Previously Reported [Member]
Revenue as reported in Form 10-Qs		$ 47,324	$ 45,663	$ 44,993		$ 42,878	$ 39,999	$ 38,207