Employee Benefits - Amounts in Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized in the Consolidated Balance Sheets:
Current accrued expenses and other current liabilities	$ 1,913	$ 1,913
Non-current other liabilities	17,301	17,014
Total accrued liabilities	19,214	18,927
Other comprehensive loss - gross actuarial (gains) losses	$ 1,200	$ (900)	$ 400
Cash surrender value of the DB SERP			$ 17,100