Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income attributable to Acadia	$ 7,419	$ 15,631
Less: net income attributable to participating securities	(44)	(162)
Income from continuing operations net of income attributable to participating securities	$ 7,375	$ 15,469
Denominator:
Weighted average shares for basic earnings per share (in shares)	83,434,083	83,634,727
Effect of dilutive securities:
Employee unvested restricted shares (in shares)	4,394	10,730
Denominator for diluted earnings per share (in shares)	83,438,477	83,645,457
Basic and diluted earnings per share (in dollars per share)	$ 0.09	$ 0.18
Series A Preferred OP Units
Anti-Dilutive Shares Excluded from Denominator:
Antidilutive securities excluded from computation of earnings per share (in shares)	188	188
Series A Preferred OP Units - Common share equivalent
Anti-Dilutive Shares Excluded from Denominator:
Antidilutive securities excluded from computation of earnings per share (in shares)	25,067	25,067
Series C Preferred OP Units
Anti-Dilutive Shares Excluded from Denominator:
Antidilutive securities excluded from computation of earnings per share (in shares)	136,593	141,593
Series C Preferred OP Units - Common share equivalent
Anti-Dilutive Shares Excluded from Denominator:
Antidilutive securities excluded from computation of earnings per share (in shares)	474,278	471,035