FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Assets and Liabilities) (Details) - Recurring basis $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) item
Assets:
Assets	$ 37,238	$ 17,358
Cash and cash equivalents
Assets:
Money market funds	32,849	14,518
Other long-term assets
Assets:
Equity, bond, and money market mutual funds held in trust related to the Voluntary Savings Plan	2,628	2,359
Interest rate swaps	1,761	481
Liabilities:
Fair value of interest rate swap, asset	1,761	481
Accrued and other long term liabilities
Liabilities:
Contingent consideration	4,472	6,970
Level 1
Assets:
Assets	35,477	16,877
Level 1 | Cash and cash equivalents
Assets:
Money market funds	32,849	14,518
Level 1 | Other long-term assets
Assets:
Equity, bond, and money market mutual funds held in trust related to the Voluntary Savings Plan	2,628	2,359
Level 2
Assets:
Assets	1,761	481
Level 2 | Other long-term assets
Assets:
Interest rate swaps	1,761	481
Liabilities:
Fair value of interest rate swap, asset	1,761	481
Level 3 | Accrued and other long term liabilities
Liabilities:
Contingent consideration	$ 4,472	$ 6,970
Level 3 | Accrued and other long term liabilities | LDS | Discount Rate
Liabilities:
Measurement input | item		0.125