Segment Reporting - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 74,800	$ 63,124
Depreciation and amortization	(30,333)	(28,576)
Property operating expenses, other operating and real estate taxes	(21,950)	(19,377)
General and administrative expenses	(8,323)	(8,470)
Operating income	14,194	6,701
Gain on disposition of properties	2,014
Interest income	2,270	3,737
Equity in earnings of unconsolidated affiliates inclusive of gains on disposition of properties	2,271	1,684
Interest expense	(17,859)	(15,890)
Income tax benefit (provision)	46	(392)
Net income (loss)	2,936	(4,160)
Net (income) loss attributable to noncontrolling interests	9,261	11,579
Net income attributable to Acadia	12,197	7,419
Real estate at cost	3,755,591	3,529,805
Total assets	4,038,875	3,938,976	$ 3,958,780
Cash paid for acquisition of real estate	32,034	46,171
Cash paid for development and property improvement costs	19,909	18,136
Operating Segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	46,687	41,628
Depreciation and amortization	(15,679)	(15,498)
Property operating expenses, other operating and real estate taxes	(11,996)	(10,894)
General and administrative expenses	0	0
Operating income	19,012	15,236
Gain on disposition of properties	0
Interest income	0	0
Equity in earnings of unconsolidated affiliates inclusive of gains on disposition of properties	2,270	1,426
Interest expense	(6,693)	(6,502)
Income tax benefit (provision)	0	0
Net income (loss)	14,589	10,160
Net (income) loss attributable to noncontrolling interests	(41)	(73)
Net income attributable to Acadia	14,548	10,087
Real estate at cost	2,114,727	2,042,280
Total assets	2,244,349	2,283,451
Cash paid for acquisition of real estate	32,034	1,337
Cash paid for development and property improvement costs	4,033	5,946
Operating Segments | Funds
Segment Reporting Information [Line Items]
Revenues	28,113	21,496
Depreciation and amortization	(14,654)	(13,078)
Property operating expenses, other operating and real estate taxes	(9,954)	(8,483)
General and administrative expenses	0	0
Operating income	3,505	(65)
Gain on disposition of properties	2,014
Interest income	0	0
Equity in earnings of unconsolidated affiliates inclusive of gains on disposition of properties	1	258
Interest expense	(11,166)	(9,388)
Income tax benefit (provision)	0	0
Net income (loss)	(5,646)	(9,195)
Net (income) loss attributable to noncontrolling interests	9,302	11,652
Net income attributable to Acadia	3,656	2,457
Real estate at cost	1,640,864	1,487,525
Total assets	1,684,757	1,546,566
Cash paid for acquisition of real estate	0	44,834
Cash paid for development and property improvement costs	15,876	12,190
Operating Segments | Structured Financing
Segment Reporting Information [Line Items]
Revenues	0	0
Depreciation and amortization	0	0
Property operating expenses, other operating and real estate taxes	0	0
General and administrative expenses	0	0
Operating income	0	0
Gain on disposition of properties	0
Interest income	2,270	3,737
Equity in earnings of unconsolidated affiliates inclusive of gains on disposition of properties	0	0
Interest expense	0	0
Income tax benefit (provision)	0	0
Net income (loss)	2,270	3,737
Net (income) loss attributable to noncontrolling interests	0	0
Net income attributable to Acadia	2,270	3,737
Real estate at cost	0	0
Total assets	109,769	108,959
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
Depreciation and amortization	0	0
Property operating expenses, other operating and real estate taxes	0	0
General and administrative expenses	(8,323)	(8,470)
Operating income	(8,323)	(8,470)
Gain on disposition of properties	0
Interest income	0	0
Equity in earnings of unconsolidated affiliates inclusive of gains on disposition of properties	0	0
Interest expense	0	0
Income tax benefit (provision)	46	(392)
Net income (loss)	(8,277)	(8,862)
Net (income) loss attributable to noncontrolling interests	0	0
Net income attributable to Acadia	(8,277)	(8,862)
Real estate at cost	0	0
Total assets	0	0
Cash paid for acquisition of real estate	0	0
Cash paid for development and property improvement costs	$ 0	$ 0