Organization (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020 shares	Dec. 31, 2020 USD ($)	Dec. 31, 2020 community	Dec. 31, 2020 apartment	Dec. 31, 2020 building	Dec. 31, 2020 investment	Dec. 31, 2020 project	Dec. 31, 2019 USD ($) shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Limited partner - ownership percentage	3.40%								3.40%
Operating Partnership units outstanding (in shares) | shares		2,294,760							2,301,653
Redemption value of operating partnership units outstanding | $			$ 544.8						$ 692.5
Number of apartment communities owned				246	2
Number of apartment units owned | apartment					60,272
Ownership interests, number of commercial buildings | building						1
Ownership interests, number of consolidated projects | project								3
Ownership Interests, number of unconsolidated projects | investment							3
Operating Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
General partner ownership interest	96.60%