Annual report pursuant to Section 13 and 15(d)

SUBSEQUENT EVENTS - Subordinated Performance Unit To OP Unit Conversions (Details)

v3.19.3.a.u2
SUBSEQUENT EVENTS - Subordinated Performance Unit To OP Unit Conversions (Details) - shares
12 Months Ended
Jan. 01, 2020
Dec. 31, 2019
Subordinated performance units    
Subsequent Event [Line Items]    
Period prior to conversion for conversion rate metric   1 year
Percentage of CAD per unit used in conversion rate calculation   110.00%
Subordinated performance units | NSA OP, LP    
Subsequent Event [Line Items]    
Minimum conversion period (in years)   2 years
Number of units converted (in units)   332,738
Subordinated performance units | DownREIT Partnership    
Subsequent Event [Line Items]    
Minimum conversion period (in years)   5 years
OP units | NSA OP, LP    
Subsequent Event [Line Items]    
Minimum conversion period (in years)   1 year
Issuance of shares/units (in shares)   863,148
OP units | DownREIT Partnership    
Subsequent Event [Line Items]    
Minimum conversion period (in years)   5 years
Issuance of shares/units (in shares)   13,475
Subsequent Event | OP units | NSA OP, LP    
Subsequent Event [Line Items]    
Issuance of shares/units (in shares) 445,701