Segment Reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 62,678	$ 43,855	$ 184,181	$ 135,818
Depreciation and amortization	(26,652)	(15,217)	(77,245)	(46,744)
Property operating expenses, other operating and real estate taxes	(18,489)	(14,515)	(55,427)	(37,791)
Impairment of asset	(3,840)	0	(3,840)	0
General and administrative expenses	(7,953)	(12,869)	(25,286)	(30,742)
Operating income	5,744	1,254	22,383	20,541
Gain on disposition of properties	12,972	0	12,972	81,965
Interest income	6,461	7,245	23,648	19,298
Equity in earnings (losses) of unconsolidated affiliates	4,001	(102)	21,044	3,592
Interest expense	(15,428)	(7,982)	(39,666)	(24,917)
Income tax provision	(465)	(89)	(1,017)	(123)
Net income	13,285	326	39,364	100,356
Net loss (income) attributable to noncontrolling interests	(418)	5,786	1,194	(47,401)
Net income attributable to Acadia	12,867	6,112	40,558	52,955
Real estate at cost	3,480,395	3,019,789	3,480,395	3,019,789
Total assets	4,092,957	3,578,519	4,092,957	3,578,519
Acquisition of real estate	70,020	274,329	138,429	292,909
Development and property improvement costs	57,539	38,531	84,554	94,421
Unallocated
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Depreciation and amortization	0	0	0	0
Property operating expenses, other operating and real estate taxes	0	0	0	0
Impairment of asset	0		0
General and administrative expenses	(7,953)	(12,869)	(25,286)	(30,742)
Operating income	(7,953)	(12,869)	(25,286)	(30,742)
Gain on disposition of properties	0		0	0
Interest income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Interest expense	0	0	0	0
Income tax provision	(465)	(89)	(1,017)	(123)
Net income	(8,418)	(12,958)	(26,303)	(30,865)
Net loss (income) attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	(8,418)	(12,958)	(26,303)	(30,865)
Real estate at cost	0	0	0	0
Total assets	0	0	0	0
Acquisition of real estate	0	0	0	0
Development and property improvement costs	0	0	0	0
Operating segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	41,196	36,376	127,130	109,176
Depreciation and amortization	(14,746)	(12,428)	(46,719)	(37,629)
Property operating expenses, other operating and real estate taxes	(10,327)	(11,612)	(33,339)	(28,460)
Impairment of asset	0		0
General and administrative expenses	0	0	0	0
Operating income	16,123	12,336	47,072	43,087
Gain on disposition of properties	0		0	0
Interest income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	805	1,495	2,348	2,668
Interest expense	(6,695)	(6,431)	(20,783)	(20,308)
Income tax provision	0	0	0	0
Net income	10,233	7,400	28,637	25,447
Net loss (income) attributable to noncontrolling interests	(353)	60	(1,157)	(2,771)
Net income attributable to Acadia	9,880	7,460	27,480	22,676
Real estate at cost	1,987,501	1,832,863	1,987,501	1,832,863
Total assets	2,237,334	2,097,386	2,237,334	2,097,386
Acquisition of real estate	0	237,729	0	244,022
Development and property improvement costs	3,359	7,296	4,355	17,518
Operating segments | Funds
Segment Reporting Information [Line Items]
Revenues	21,482	7,479	57,051	26,642
Depreciation and amortization	(11,906)	(2,789)	(30,526)	(9,115)
Property operating expenses, other operating and real estate taxes	(8,162)	(2,903)	(22,088)	(9,331)
Impairment of asset	(3,840)		(3,840)
General and administrative expenses	0	0	0	0
Operating income	(2,426)	1,787	597	8,196
Gain on disposition of properties	12,972		12,972	81,965
Interest income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	3,196	(1,597)	18,696	924
Interest expense	(8,733)	(1,551)	(18,883)	(4,609)
Income tax provision	0	0	0	0
Net income	5,009	(1,361)	13,382	86,476
Net loss (income) attributable to noncontrolling interests	(65)	5,726	2,351	(44,630)
Net income attributable to Acadia	4,944	4,365	15,733	41,846
Real estate at cost	1,492,894	1,186,926	1,492,894	1,186,926
Total assets	1,605,429	1,214,317	1,605,429	1,214,317
Acquisition of real estate	70,020	36,600	138,429	48,887
Development and property improvement costs	54,180	31,235	80,199	76,903
Operating segments | Structured Financing
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Depreciation and amortization	0	0	0	0
Property operating expenses, other operating and real estate taxes	0	0	0	0
Impairment of asset	0		0
General and administrative expenses	0	0	0	0
Operating income	0	0	0	0
Gain on disposition of properties	0		0	0
Interest income	6,461	7,245	23,648	19,298
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Interest expense	0	0	0	0
Income tax provision	0	0	0	0
Net income	6,461	7,245	23,648	19,298
Net loss (income) attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	6,461	7,245	23,648	19,298
Real estate at cost	0	0	0	0
Total assets	250,194	266,816	250,194	266,816
Acquisition of real estate	0	0	0	0
Development and property improvement costs	$ 0	$ 0	$ 0	$ 0