Fair Value of Assets and Liabilities - Summary of Changes in Fair Value of Level 3 Financial Instruments (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Fair Value Disclosures [Abstract] | ||||
| Balance at December 31, 2017 | $ 998 | |||
| Change in fair value during the period | $ 219 | $ 86 | 303 | $ 86 |
| Balance at June 30, 2018 | $ 1,301 | $ 1,301 | ||