SELF STORAGE PROPERTY ACQUISITIONS AND DISPOSITIONS - Acquisitions (Details) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2017
USD ($)
property
|
Sep. 30, 2017
USD ($)
property
|
Jun. 30, 2017
USD ($)
property
|
Mar. 31, 2017
USD ($)
property
|
Dec. 31, 2016
USD ($)
property
|
Sep. 30, 2016
USD ($)
property
|
Jun. 30, 2016
USD ($)
property
|
Mar. 31, 2016
USD ($)
property
|
Dec. 31, 2017
USD ($)
property
|
Dec. 31, 2016
USD ($)
property
|
Dec. 31, 2015
USD ($)
|
|
| Business Acquisition [Line Items] | |||||||||||
| Consideration given, cash and acquisition costs | $ 0 | $ 19,933 | $ 0 | ||||||||
| Business combination, debt adjustment on assumed mortgages | $ 7,200 | $ 7,200 | |||||||||
| 2017 Acquisitions [Member] | |||||||||||
| Business Acquisition [Line Items] | |||||||||||
| Number of self storage properties acquired | property | 31 | 19 | 10 | 5 | 65 | ||||||
| Consideration given, cash and acquisition costs | $ 181,809 | $ 122,742 | $ 60,672 | $ 26,780 | $ 392,003 | ||||||
| Consideration given, value of OP Equity | 17,019 | 267 | 8,931 | 4,964 | 31,181 | ||||||
| Liabilities assumed, mortgages | 0 | 0 | 0 | 0 | 0 | ||||||
| Liabilities assumed, other | 2,220 | 826 | 387 | 183 | 3,616 | ||||||
| Total consideration given and liabilities assumed | $ 201,048 | $ 123,835 | $ 69,990 | $ 31,927 | $ 426,800 | ||||||
| 2016 Acquisitions [Member] | |||||||||||
| Business Acquisition [Line Items] | |||||||||||
| Number of self storage properties acquired | property | 31 | 34 | 25 | 17 | 107 | ||||||
| Consideration given, cash and acquisition costs | $ 208,707 | $ 199,890 | $ 61,263 | $ 63,300 | $ 533,160 | ||||||
| Consideration given, value of OP Equity | 16,871 | 4,841 | 80,986 | 19,068 | 121,766 | ||||||
| Liabilities assumed, mortgages | 0 | 0 | 55,767 | 5,861 | 61,628 | ||||||
| Liabilities assumed, other | 2,125 | 896 | 1,212 | 584 | 4,817 | ||||||
| Total consideration given and liabilities assumed | $ 227,703 | $ 205,627 | $ 199,228 | $ 88,813 | $ 721,371 | ||||||