Leases and Rentals - Schedule of Capital Lease Obligations (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Capital Lease Obligations [Abstract] | ||
| Other accrued liabilities | $ 73 | $ 69 |
| Other non-current liabilities | 48 | 111 |
| Total | $ 121 | $ 180 |