BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair Value Accounting (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets (liabilities)
Other long-term assets	$ 5,038	$ 4,461
Recurring basis | Level 1
Assets (liabilities)
Pension plan assets	5,231	5,362
Other long-term assets	3,962	3,929
Recurring basis | Level 2
Assets (liabilities)
Interest rate swaps	$ 434
Interest rate swaps		$ (196)