Equity Equity (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Equity Note [Line Items]
Balance, December 31, 2014	$ 647,576
Share-based compensation	1
Balance, March 31, 2015	669,559
Common Stock [Member]
Equity Note [Line Items]
Balance, December 31, 2014	5,771
Issuance of common shares	31
Balance, March 31, 2015	5,802
Additional Paid-in Capital [Member]
Equity Note [Line Items]
Balance, December 31, 2014	758,079
Share-based compensation	(1,931)
Issuance of common shares	264
Balance, March 31, 2015	760,274
Accumulated Distributions in Excess of Net Income [Member]
Equity Note [Line Items]
Balance, December 31, 2014	(114,551)
Net income applicable to AERC	30,284
Common share dividends declared	(12,378)
Balance, March 31, 2015	(96,644)
Accumulated Other Comprehensive Income (Loss) [Member]
Equity Note [Line Items]
Balance, December 31, 2014	(1,093)
Changes in fair value of hedge instruments	875
Balance, March 31, 2015	(218)
Treasury Stock [Member]
Equity Note [Line Items]
Balance, December 31, 2014	980
Share-based compensation	(1,237)
Purchase of common shares	(1,187)
Issuance of common shares	925
Balance, March 31, 2015	5
Noncontrolling Interest [Member]
Equity Note [Line Items]
Balance, December 31, 2014	350
Balance, March 31, 2015	$ 350