Segment Reporting - Summary of Segment Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 51,281,000	$ 73,327,000	$ 186,474,000	$ 217,543,000
Depreciation and amortization	(34,457,000)	(32,170,000)	(101,627,000)	(92,807,000)
Property operating expenses, other operating and real estate taxes	(22,248,000)	(23,405,000)	(73,518,000)	(66,947,000)
General and administrative expenses	(8,625,000)	(8,222,000)	(26,415,000)	(25,579,000)
Impairment charges		(321,000)	(51,549,000)	(1,721,000)
Gain on disposition of properties	24,000	12,056,000	509,000	14,070,000
Operating (loss) income	(14,025,000)	21,265,000	(66,126,000)	44,559,000
Interest income	2,132,000		7,156,000
Interest and other income	2,132,000	6,782,000	7,156,000	13,194,000
Realized and unrealized holding (losses) gains on investments and other	(7,946,000)		79,335,000
Equity in (losses) earnings of unconsolidated affiliates	(624,000)	1,299,000	(155,000)	7,129,000
Interest expense	(17,752,000)	(19,103,000)	(54,373,000)	(56,721,000)
Income tax (provision) benefit	(74,000)	(1,403,000)	741,000	(1,622,000)
Net (loss) income	(38,289,000)	8,840,000	(33,422,000)	6,539,000
Net loss attributable to noncontrolling interests	29,259,000	1,618,000	35,388,000	25,196,000
Net (loss) income attributable to Acadia	(9,030,000)	10,458,000	1,966,000	31,735,000
Real estate at cost	4,168,291,000	4,012,134,000	4,168,291,000	4,012,134,000
Total assets	4,251,408,000	4,329,545,000	4,251,408,000	4,329,545,000	$ 4,309,114,000
Cash paid for acquisition of real estate			21,208,000	256,647,000
Cash paid for development and property improvement costs			27,949,000	77,636,000
Core Portfolio
Segment Reporting Information [Line Items]
Realized and unrealized holding (losses) gains on investments and other			0
Operating Segments | Core Portfolio
Segment Reporting Information [Line Items]
Revenues	38,848,000	42,142,000	117,383,000	131,356,000
Depreciation and amortization	(17,987,000)	(15,179,000)	(53,193,000)	(45,949,000)
Property operating expenses, other operating and real estate taxes	(12,709,000)	(11,205,000)	(42,484,000)	(34,730,000)
General and administrative expenses	0	0	0	0
Impairment charges		0	0	0
Gain on disposition of properties	0	0	0	0
Operating (loss) income	8,152,000	15,758,000	21,706,000	50,677,000
Interest income	0		0
Interest and other income		0		327,000
Realized and unrealized holding (losses) gains on investments and other	0		0
Equity in (losses) earnings of unconsolidated affiliates	(784,000)	1,798,000	(212,000)	7,322,000
Interest expense	(8,276,000)	(7,333,000)	(25,127,000)	(20,866,000)
Income tax (provision) benefit	0	0	0	0
Net (loss) income	(908,000)	10,223,000	(3,633,000)	37,460,000
Net loss attributable to noncontrolling interests	1,407,000	263,000	7,691,000	648,000
Net (loss) income attributable to Acadia	499,000	10,486,000	4,058,000	38,108,000
Real estate at cost	2,365,426,000	2,190,281,000	2,365,426,000	2,190,281,000
Total assets	2,291,730,000	2,316,683,000	2,291,730,000	2,316,683,000
Cash paid for acquisition of real estate			19,963,000	82,125,000
Cash paid for development and property improvement costs			7,522,000	19,059,000
Operating Segments | Opportunity Funds
Segment Reporting Information [Line Items]
Revenues	12,433,000	31,185,000	69,091,000	86,187,000
Depreciation and amortization	(16,470,000)	(16,991,000)	(48,434,000)	(46,858,000)
Property operating expenses, other operating and real estate taxes	(9,539,000)	(12,200,000)	(31,034,000)	(32,217,000)
General and administrative expenses	0	0	0	0
Impairment charges		(321,000)	(51,549,000)	(1,721,000)
Gain on disposition of properties	24,000	12,056,000	509,000	14,070,000
Operating (loss) income	(13,552,000)	13,729,000	(61,417,000)	19,461,000
Interest income	0		0
Interest and other income		5,034,000		6,620,000
Realized and unrealized holding (losses) gains on investments and other	(7,906,000)		79,845,000
Equity in (losses) earnings of unconsolidated affiliates	160,000	(499,000)	57,000	(193,000)
Interest expense	(9,476,000)	(11,770,000)	(29,246,000)	(35,855,000)
Income tax (provision) benefit	0	0	0	0
Net (loss) income	(30,774,000)	6,494,000	(10,761,000)	(9,967,000)
Net loss attributable to noncontrolling interests	27,852,000	1,355,000	27,697,000	24,548,000
Net (loss) income attributable to Acadia	(2,922,000)	7,849,000	16,936,000	14,581,000
Real estate at cost	1,802,865,000	1,821,853,000	1,802,865,000	1,821,853,000
Total assets	1,824,880,000	1,918,055,000	1,824,880,000	1,918,055,000
Cash paid for acquisition of real estate			1,245,000	174,522,000
Cash paid for development and property improvement costs			20,427,000	58,577,000
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 charges		0	0	0
Gain on disposition of properties	0	0	0	0
Operating (loss) income	0	0	0	0
Interest income	2,132,000		7,156,000
Interest and other income		1,748,000		6,247,000
Realized and unrealized holding (losses) gains on investments and other	(40,000)		(510,000)
Equity in (losses) earnings of unconsolidated affiliates	0	0	0	0
Interest expense	0	0	0	0
Income tax (provision) benefit	0	0	0	0
Net (loss) income	2,092,000	1,748,000	6,646,000	6,247,000
Net loss attributable to noncontrolling interests	0	0	0	0
Net (loss) income attributable to Acadia	2,092,000	1,748,000	6,646,000	6,247,000
Real estate at cost	0	0	0	0
Total assets	134,798,000	94,807,000	134,798,000	94,807,000
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	(8,625,000)	(8,222,000)	(26,415,000)	(25,579,000)
Impairment charges		0	0	0
Gain on disposition of properties	0	0	0	0
Operating (loss) income	(8,625,000)	(8,222,000)	(26,415,000)	(25,579,000)
Interest income	0		0
Interest and other income		0		0
Realized and unrealized holding (losses) gains on investments and other	0		0
Equity in (losses) earnings of unconsolidated affiliates	0	0	0	0
Interest expense	0	0	0	0
Income tax (provision) benefit	(74,000)	(1,403,000)	741,000	(1,622,000)
Net (loss) income	(8,699,000)	(9,625,000)	(25,674,000)	(27,201,000)
Net loss attributable to noncontrolling interests	0	0	0	0
Net (loss) income attributable to Acadia	(8,699,000)	(9,625,000)	(25,674,000)	(27,201,000)
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