v3.8.0.1

Non-Controlling Interests - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Minority Interest [Line Items] |  |  |
Properties contributed as part of UPREIT transactions, value | $ 10,498 | $ 7,190 | $ 57,583
Properties contributed as part of UPREIT transactions, value, net of debt assumed | $ 112,949 | $ 102,451 | $ 95,261
Membership units, issued | 1,551 | 1,427 | 1,330
Membership units, outstanding | 1,551 | 1,427 | 1,330
Percentage of economic interests owned by non-controlling interests | 7.60% | 8.60% | 10.40%
Number of membership units exchanged | 37,000 | 0 | 0
Value of common stock issued upon exchange of membership units | $ 0 |  |
Rental income related to UPREIT transactions | 13,153 | $ 11,843 | $ 5,259
Additional Paid-in Capital |  |  |
Minority Interest [Line Items] |  |  |
Value of common stock issued upon exchange of membership units | $ 2,986 |  |
Common Stock |  |  |
Minority Interest [Line Items] |  |  |
Number of common stock issued upon exchange of membership units | 37,000 |  |
Value of common stock issued upon exchange of membership units | $ 0 |  |

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