Quarterly report pursuant to Section 13 or 15(d)

NONCONTROLLING INTERESTS - Equity Interests (Details)

v3.5.0.2
NONCONTROLLING INTERESTS - Equity Interests (Details) - shares
 9 Months Ended
Sep. 30, 2016
Dec. 31, 2015
Partnership Subsidiaries [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 44,289,967 39,865,541
OP units [Member]    
Noncontrolling Interest [Line Items]    
Shares issued in conversion (in shares) 1,293,860  
OP units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 25,503,628 21,556,006
Number of units issued (in shares) 3,499,542  
Redemption of Units (in shares) 845,780  
OP units [Member] | DownREIT Partnership [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 1,834,786 1,834,786
Subordinated performance units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 11,011,649 9,302,989
Subordinated performance units [Member] | DownREIT Partnership [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 4,386,999 4,386,999
LTIP units [Member]    
Noncontrolling Interest [Line Items]    
Number of units issued (in shares) 180,304  
Share converted (in shares) 1,293,860  
Shares forfeited (in shares) 118,300  
LTIP units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 1,552,905 2,784,761