Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUES:
Total revenues	$ 719,556	$ 770,602	$ 840,247
OPERATING EXPENSES:
Depreciation and amortization	320,943	317,283	329,394
General and administrative expenses	46,377	49,615	49,636
Provision for real estate impairment loss	47,281	0	0
Other expenses (income), net	73,860	16,737	(574)
Total operating expenses	737,497	644,876	664,101
Interest income	12,374	9,300	9,326
Interest expense	(160,359)	(150,888)	(179,805)
Gain on dispositions of real estate and the Asset Management business	119,215	503,168	677,463
Mezzanine / Unconsolidated partnerships investment income, net	27,576	1,531	0
Loss from unconsolidated real estate partnerships	0	0	(864)
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations	(19,135)	488,837	682,266
Income tax (expense) benefit (Note 11)	(95,437)	(305)	13,346
(Loss) income from continuing operations	(114,572)	488,532	695,612
Income from discontinued operations, net of tax	11,228	19,495	20,991
Net (loss) income	(103,344)	508,027	716,603
Noncontrolling interests:
Net loss (income) attributable to noncontrolling interests in consolidated real estate partnerships	798	(187)	(8,220)
Net income attributable to preferred noncontrolling interests in AIR Operating Partnership	(7,019)	(7,708)	(7,739)
Net loss (income) attributable to common noncontrolling interests in AIR Operating Partnership	5,438	(26,049)	(34,417)
Net income attributable to noncontrolling interests	783	33,944	50,376
Net (loss) income attributable to AIR	(104,127)	474,083	666,227
Net income attributable to AIR preferred stockholders	0	(7,335)	(8,593)
Net income attributable to participating securities	(202)	(604)	(1,037)
Net (loss) income attributable to AIR common stockholders	$ (104,329)	$ 466,144	$ 656,597
(Loss) earnings per common share – basic
(Loss) income from continuing operations attributable to AIR per common share	$ (0.94)	$ 3.75	$ 5.21
Income from discontinued operations attributable to AIR per common share	0.09	0.16	0.17
Net (loss) income attributable to AIR per common share – basic	(0.85)	3.91	5.38
(Loss) earnings per common share – diluted
(Loss) income from continuing operations attributable to AIR per common share	(0.94)	3.74	5.20
Income from discontinued operations attributable to AIR per common share	0.09	0.16	0.17
Net (loss) income attributable to AIR per common share – diluted	$ (0.85)	$ 3.90	$ 5.37
Weighted average common shares/units outstanding - basic	122,446	119,307	122,097
Weighted average common shares/units outstanding - diluted	122,446	119,533	122,243
Net loss (income) attributable to noncontrolling interests in consolidated real estate partnerships	$ 798	$ (187)	$ (8,220)
AIMCO Properties, LP [Member]
REVENUES:
Total revenues	719,556	770,602	840,247
OPERATING EXPENSES:
Depreciation and amortization	320,943	317,283	329,394
General and administrative expenses	46,377	49,615	49,636
Provision for real estate impairment loss	47,281	0	0
Other expenses (income), net	73,860	16,737	(574)
Total operating expenses	737,497	644,876	664,101
Interest income	12,374	9,300	9,326
Interest expense	(160,359)	(150,888)	(179,805)
Gain on dispositions of real estate and the Asset Management business	119,215	503,168	677,463
Mezzanine / Unconsolidated partnerships investment income, net	27,576	1,531	0
Loss from unconsolidated real estate partnerships	0	0	(864)
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations	(19,135)	488,837	682,266
Income tax (expense) benefit (Note 11)	(95,437)	(305)	13,346
Income from discontinued operations, net of tax	11,228	19,495	20,991
Net (loss) income	(103,344)	508,027	716,603
Noncontrolling interests:
Net loss (income) attributable to noncontrolling interests in consolidated real estate partnerships	798	(187)	(8,220)
Net (loss) income attributable to AIR	(102,546)	507,840	708,383
Net income attributable to AIR preferred stockholders	(7,019)	(15,043)	(16,332)
Net income attributable to participating securities	(202)	(620)	(1,177)
Net (loss) income attributable to AIR common stockholders	$ (109,767)	$ 492,177	$ 690,874
(Loss) earnings per common share – basic
(Loss) income from continuing operations attributable to AIR per common share	$ (0.94)	$ 3.75	$ 5.22
Income from discontinued operations attributable to AIR per common share	0.09	0.16	0.16
Net (loss) income attributable to AIR per common share – basic	(0.85)	3.91	5.38
(Loss) earnings per common share – diluted
(Loss) income from continuing operations attributable to AIR per common share	(0.94)	3.74	5.22
Net (loss) income attributable to AIR per common share – diluted	(0.85)	3.90	5.38
Income from discontinued operations attributable to the AIR Operating Partnership per common unit	$ 0.09	$ 0.16	$ 0.16
Weighted average common shares/units outstanding - basic	128,775	125,893	128,323
Weighted average common shares/units outstanding - diluted	128,775	126,164	128,469
(Loss) income from continuing operations	$ (114,572)	$ 488,532	$ 695,612
Net loss (income) attributable to noncontrolling interests in consolidated real estate partnerships	798	(187)	(8,220)
Rental and Other Property Revenues [Member]
REVENUES:
Total revenues	719,556	770,602	790,430
OPERATING EXPENSES:
Property operating expenses	249,036	261,241	264,724
Asset Management Business [Member]
REVENUES:
Total revenues	0	0	49,817
OPERATING EXPENSES:
Property operating expenses	0	0	20,921
Asset Management Business [Member] | AIMCO Properties, LP [Member]
REVENUES:
Total revenues	0	0	49,817
OPERATING EXPENSES:
Property operating expenses	0	0	20,921
Real Estate | AIMCO Properties, LP [Member]
REVENUES:
Total revenues	719,556	770,602	790,430
OPERATING EXPENSES:
Property operating expenses	$ 249,036	$ 261,241	$ 264,724