Segment Reporting - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 66,075	$ 62,678	$ 192,768	$ 184,181
Depreciation and amortization	(28,676)	(26,652)	(86,755)	(77,245)
Property operating expenses, other operating and real estate taxes	(22,469)	(18,489)	(61,706)	(55,427)
General and administrative expenses	(7,982)	(7,953)	(24,359)	(25,286)
Impairment charge		(3,840)		(3,840)
Operating income	6,948	5,744	19,948	22,383
Gain on disposition of properties, net of tax	5,107	12,972	5,140	12,972
Interest income	3,513	6,461	10,539	23,648
Equity in earnings (losses) of unconsolidated affiliates	376	4,001	7,079	21,044
Interest expense	(18,077)	(15,428)	(50,882)	(39,666)
Income tax provision	(464)	(465)	(851)	(1,017)
Net (loss) income	(2,597)	13,285	(9,027)	39,364
Net (income) loss attributable to noncontrolling interests	11,822	(418)	33,336	1,194
Net income attributable to Acadia	9,225	12,867	24,309	40,558
Real estate at cost	3,613,174	3,480,395	3,613,174	3,480,395
Total assets	3,918,716	4,092,957	3,918,716	4,092,957	$ 3,960,247
Cash paid for acquisition of real estate			104,902	138,429
Cash paid for development and property improvement costs			66,238	84,554
Operating Segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	42,290	41,196	124,456	127,130
Depreciation and amortization	(14,856)	(14,746)	(45,283)	(46,719)
Property operating expenses, other operating and real estate taxes	(12,195)	(10,327)	(33,599)	(33,339)
General and administrative expenses	0	0	0	0
Impairment charge		0		0
Operating income	15,239	16,123	45,574	47,072
Gain on disposition of properties, net of tax	0	0	0	0
Interest income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	2,005	805	5,171	2,348
Interest expense	(6,972)	(6,695)	(20,475)	(20,783)
Income tax provision	0	0	0	0
Net (loss) income	10,272	10,233	30,270	28,637
Net (income) loss attributable to noncontrolling interests	115	(353)	241	(1,157)
Net income attributable to Acadia	10,387	9,880	30,511	27,480
Real estate at cost	2,060,024	1,987,501	2,060,024	1,987,501
Total assets	2,234,521	2,237,334	2,234,521	2,237,334
Cash paid for acquisition of real estate			1,343	0
Cash paid for development and property improvement costs			22,892	4,355
Operating Segments | Funds
Segment Reporting Information [Line Items]
Revenues	23,785	21,482	68,312	57,051
Depreciation and amortization	(13,820)	(11,906)	(41,472)	(30,526)
Property operating expenses, other operating and real estate taxes	(10,274)	(8,162)	(28,107)	(22,088)
General and administrative expenses	0	0	0	0
Impairment charge		(3,840)		(3,840)
Operating income	(309)	(2,426)	(1,267)	597
Gain on disposition of properties, net of tax	5,107	12,972	5,140	12,972
Interest income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	(1,629)	3,196	1,908	18,696
Interest expense	(11,105)	(8,733)	(30,407)	(18,883)
Income tax provision	0	0	0	0
Net (loss) income	(7,936)	5,009	(24,626)	13,382
Net (income) loss attributable to noncontrolling interests	11,707	(65)	33,095	2,351
Net income attributable to Acadia	3,771	4,944	8,469	15,733
Real estate at cost	1,553,150	1,492,894	1,553,150	1,492,894
Total assets	1,574,785	1,605,429	1,574,785	1,605,429
Cash paid for acquisition of real estate			103,559	138,429
Cash paid for development and property improvement costs			43,346	80,199
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
General and administrative expenses	0	0	0	0
Impairment charge		0		0
Operating income	0	0	0	0
Gain on disposition of properties, net of tax	0	0	0	0
Interest income	3,513	6,461	10,539	23,648
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 (loss) income	3,513	6,461	10,539	23,648
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	3,513	6,461	10,539	23,648
Real estate at cost	0	0	0	0
Total assets	109,410	250,194	109,410	250,194
Cash paid for acquisition of real estate			0	0
Cash paid for development and property improvement costs			0	0
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
General and administrative expenses	(7,982)	(7,953)	(24,359)	(25,286)
Impairment charge		0		0
Operating income	(7,982)	(7,953)	(24,359)	(25,286)
Gain on disposition of properties, net of tax	0	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	(464)	(465)	(851)	(1,017)
Net (loss) income	(8,446)	(8,418)	(25,210)	(26,303)
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	(8,446)	(8,418)	(25,210)	(26,303)
Real estate at cost	0	0	0	0
Total assets	$ 0	$ 0	0	0
Cash paid for acquisition of real estate			0	0
Cash paid for development and property improvement costs			$ 0	$ 0