Segment Reporting - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 73,327	$ 65,527	$ 217,543	$ 189,954
Depreciation and amortization	(32,170)	(28,676)	(92,807)	(86,755)
Property operating expenses, other operating and real estate taxes	(23,405)	(21,921)	(66,947)	(58,892)
General and administrative expenses	(8,222)	(7,982)	(25,579)	(24,359)
Impairment charge	(321)		(1,721)
Gain on disposition of properties	12,056	5,107	14,070	5,140
Operating income	21,265	12,055	44,559	25,088
Interest income	1,748	3,513	6,247	10,539
Other income	5,034		6,947
Interest and Other Income				10,539
Equity in earnings (losses) of unconsolidated affiliates	1,299	376	7,129	7,079
Interest expense	(19,103)	(18,077)	(56,721)	(50,882)
Income tax provision	(1,403)	(464)	(1,622)	(851)
Net income (loss)	8,840	(2,597)	6,539	(9,027)
Net loss attributable to noncontrolling interests	1,618	11,822	25,196	33,336
Net income attributable to Acadia	10,458	9,225	31,735	24,309
Real estate at cost	4,012,134	3,613,174	4,012,134	3,613,174
Total assets	4,329,545	3,918,716	4,329,545	3,918,716	$ 3,958,780
Acquisition of real estate			256,647	104,902
Cash paid for development and property improvement costs			77,636	66,238
Operating Segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	42,142	41,742	131,356	122,959
Depreciation and amortization	(15,179)	(14,856)	(45,949)	(45,283)
Property operating expenses, other operating and real estate taxes	(11,205)	(11,910)	(34,730)	(32,102)
General and administrative expenses	0	0	0	0
Impairment charge	0		0
Gain on disposition of properties	0	0	0	0
Operating income	15,758	14,976	50,677	45,574
Interest income	0	0	0
Other income	0		327
Interest and Other Income				0
Equity in earnings (losses) of unconsolidated affiliates	1,798	2,005	7,322	5,171
Interest expense	(7,333)	(6,972)	(20,866)	(20,475)
Income tax provision	0	0	0	0
Net income (loss)	10,223	10,009	37,460	30,270
Net loss attributable to noncontrolling interests	263	115	648	241
Net income attributable to Acadia	10,486	10,124	38,108	30,511
Real estate at cost	2,190,281	2,060,024	2,190,281	2,060,024
Total assets	2,316,683	2,234,521	2,316,683	2,234,521
Acquisition of real estate			82,125	1,343
Cash paid for development and property improvement costs			19,059	22,892
Operating Segments | Opportunity Funds
Segment Reporting Information [Line Items]
Revenues	31,185	23,785	86,187	66,995
Depreciation and amortization	(16,991)	(13,820)	(46,858)	(41,472)
Property operating expenses, other operating and real estate taxes	(12,200)	(10,011)	(32,217)	(26,790)
General and administrative expenses	0	0	0	0
Impairment charge	(321)		(1,721)
Gain on disposition of properties	12,056	5,107	14,070	5,140
Operating income	13,729	5,061	19,461	3,873
Interest income	0	0	0
Other income	5,034		6,620
Interest and Other Income				0
Equity in earnings (losses) of unconsolidated affiliates	(499)	(1,629)	(193)	1,908
Interest expense	(11,770)	(11,105)	(35,855)	(30,407)
Income tax provision	0	0	0	0
Net income (loss)	6,494	(7,673)	(9,967)	(24,626)
Net loss attributable to noncontrolling interests	1,355	11,707	24,548	33,095
Net income attributable to Acadia	7,849	4,034	14,581	8,469
Real estate at cost	1,821,853	1,553,150	1,821,853	1,553,150
Total assets	1,918,055	1,574,785	1,918,055	1,574,785
Acquisition of real estate			174,522	103,559
Cash paid for development and property improvement costs			58,577	43,346
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
Gain on disposition of properties	0	0	0	0
Operating income	0	0	0	0
Interest income	1,748	3,513	6,247
Other income	0		0
Interest and Other Income				10,539
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 (loss)	1,748	3,513	6,247	10,539
Net loss attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	1,748	3,513	6,247	10,539
Real estate at cost	0	0	0	0
Total assets	94,807	109,410	94,807	109,410
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	(8,222)	(7,982)	(25,579)	(24,359)
Impairment charge	0		0
Gain on disposition of properties	0	0	0	0
Operating income	(8,222)	(7,982)	(25,579)	(24,359)
Interest income	0	0	0
Other income	0		0
Interest and Other Income				0
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Interest expense	0	0	0	0
Income tax provision	(1,403)	(464)	(1,622)	(851)
Net income (loss)	(9,625)	(8,446)	(27,201)	(25,210)
Net loss attributable to noncontrolling interests	0	0	0	0
Net income attributable to Acadia	(9,625)	(8,446)	(27,201)	(25,210)
Real estate at cost	0	0	0	0
Total assets	$ 0	$ 0	0	0
Acquisition of real estate			0	0
Cash paid for development and property improvement costs			$ 0	$ 0