Sale of Real Estate - Schedule of Sale of Real Estate (Detail) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2017
USD ($)
Property
|
Dec. 31, 2016
USD ($)
Property
|
Dec. 31, 2015
USD ($)
Property
|
|
| Real Estate [Abstract] | |||
| Number of properties disposed | Property | 13 | 9 | 6 |
| Aggregate sale price | $ 66,532 | $ 39,500 | $ 19,455 |
| Aggregate carrying value | 50,339 | 32,665 | 18,672 |
| Additional sales expenses | 3,201 | 910 | 1,496 |
| Gain (loss) on sale of real estate | $ 12,992 | $ 5,925 | $ (713) |