Segment Reporting (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	3
Revenues	$ 63,124	$ 61,999
Depreciation and amortization	(28,576)	(24,536)
Property operating expenses, other operating and real estate taxes	(19,377)	(19,097)
General and administrative expenses	(8,470)	(8,469)
Operating income	6,701	9,897
Interest income	3,737	8,984
Equity in earnings (losses) of unconsolidated affiliates	1,684	12,703
Interest expense	(15,890)	(11,488)
Income tax provision	(392)	(125)
Net (loss) income	(4,160)	19,971
Net loss (income) attributable to noncontrolling interests	11,579	(4,340)
Net income attributable to Acadia	7,419	15,631
Real estate at cost	3,529,805	3,463,566
Total assets	3,938,976	4,020,589
Cash paid for acquisition of real estate	46,171	34,688
Cash paid for development and property improvement costs	18,136	27,015
Operating segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	41,628	44,446
Depreciation and amortization	(15,498)	(16,439)
Property operating expenses, other operating and real estate taxes	(10,894)	(12,853)
General and administrative expenses	0	0
Operating income	15,236	15,154
Interest income	0	0
Equity in earnings (losses) of unconsolidated affiliates	1,426	560
Interest expense	(6,502)	(7,155)
Income tax provision	0	0
Net (loss) income	10,160	8,559
Net loss (income) attributable to noncontrolling interests	(73)	(432)
Net income attributable to Acadia	10,087	8,127
Real estate at cost	2,042,280	1,983,365
Total assets	2,283,451	2,246,037
Cash paid for acquisition of real estate	1,337	0
Cash paid for development and property improvement costs	5,946	996
Operating segments | Funds
Segment Reporting Information [Line Items]
Revenues	21,496	17,553
Depreciation and amortization	(13,078)	(8,097)
Property operating expenses, other operating and real estate taxes	(8,483)	(6,244)
General and administrative expenses	0	0
Operating income	(65)	3,212
Interest income	0	0
Equity in earnings (losses) of unconsolidated affiliates	258	12,143
Interest expense	(9,388)	(4,333)
Income tax provision	0	0
Net (loss) income	(9,195)	11,022
Net loss (income) attributable to noncontrolling interests	11,652	(3,908)
Net income attributable to Acadia	2,457	7,114
Real estate at cost	1,487,525	1,480,201
Total assets	1,546,566	1,498,045
Cash paid for acquisition of real estate	44,834	34,688
Cash paid for development and property improvement costs	12,190	26,019
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
Interest income	3,737	8,984
Equity in earnings (losses) of unconsolidated affiliates	0	0
Interest expense	0	0
Income tax provision	0	0
Net (loss) income	3,737	8,984
Net loss (income) attributable to noncontrolling interests	0	0
Net income attributable to Acadia	3,737	8,984
Real estate at cost	0	0
Total assets	108,959	276,507
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	(8,470)	(8,469)
Operating income	(8,470)	(8,469)
Interest income	0	0
Equity in earnings (losses) of unconsolidated affiliates	0	0
Interest expense	0	0
Income tax provision	(392)	(125)
Net (loss) income	(8,862)	(8,594)
Net loss (income) attributable to noncontrolling interests	0	0
Net income attributable to Acadia	(8,862)	(8,594)
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