Notes Payable (Schedule of Future Principal Payments Due on Notes Payable) (Details) - USD ($) $ in Thousands |
Mar. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Debt Instrument [Line Items] | ||
| 2020 | $ 4,530 | |
| 2021 | 155,207 | |
| 2022 | 279,922 | |
| 2023 | 252,712 | |
| Thereafter | 138,429 | |
| Total | $ 832,481 | |
| Notes Payable [Member] | ||
| Debt Instrument [Line Items] | ||
| 2019 | $ 1,937 | |
| 2020 | 4,530 | |
| 2021 | 155,207 | |
| 2022 | 164,971 | |
| 2023 | 2,712 | |
| Thereafter | 138,429 | |
| Total | $ 467,786 |