Borrowings - Secured Credit Facilities (Details) - USD ($) $ in Thousands |
6 Months Ended | |
|---|---|---|
Jun. 30, 2019 |
Dec. 31, 2018 |
|
| Debt Instrument [Line Items] | ||
| Amount outstanding | $ 134,129 | $ 163,800 |
| Line of Credit | ||
| Debt Instrument [Line Items] | ||
| Variable rate basis | LIBOR | |
| Line of Credit | Minimum | ||
| Debt Instrument [Line Items] | ||
| Loan margin percentage | 2.75% | |
| Maturity date | Jun. 30, 2021 | |
| Line of Credit | Maximum | ||
| Debt Instrument [Line Items] | ||
| Loan margin percentage | 3.60% | |
| Maturity date | Nov. 30, 2022 |