Discontinued Operations - Summarized Results of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUES:
Rental and other property revenues									$ 144,757	$ 143,692	$ 132,163
OPERATING EXPENSES:
Depreciation and amortization									72,729	62,887	48,392
Total operating expenses									126,336	112,646	92,556
Interest income									2,076	2,125	1,592
Interest expense									(17,972)	(17,918)	(20,829)
Loss from unconsolidated real estate partnerships									0	0	(864)
Income before income tax benefit (expense)									3,289	16,055	21,310
Income tax benefit (expense)									7,939	3,440	(319)
Income from discontinued operations, net of tax	$ 1,459	$ 2,578	$ 3,125	$ 4,066	$ 4,088	$ 3,885	$ 6,178	$ 5,344	11,228	19,495	20,991
Net loss (income) attributable to noncontrolling interests in consolidated real estate partnerships									404	189	(5)
Net income from discontinued operations attributable to AIR									11,632	19,684	20,986
Discontinued Operations [Member]
OPERATING EXPENSES:
Property operating expenses									51,710	49,502	45,372
Other expenses (income), net									1,897	257	(1,208)
Loss from unconsolidated real estate partnerships									$ 764	$ 802	$ 940