LEASES - Undiscounted future lease payments for operating and finance leases (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating Leases
2019 (excluding the three months ended March 31, 2019)	$ 2,847
2020	3,187
2021	2,586
2022	2,187
2023	1,733
2024 and thereafter	14,572
Total lease payments	27,112
Less interest	(5,001)
Total	22,111
Finance Leases
2019 (excluding the three months ended March 31, 2019)	814
2020	64
Total lease payments	878
Less interest	(18)
Total	860
Accrued liabilities, Operating Leases	$ 3,028
Accrued liabilities, Operating Leases	us-gaap:AccruedLiabilitiesCurrent
Accrued liabilities, Finance Leases	$ 860
Accrued liabilities, Finance Leases	us-gaap:AccruedLiabilitiesCurrent
Other liabilities, Operating Leases	$ 19,083
Other liabilities, Operating Leases	us-gaap:OtherLiabilitiesNoncurrent
Other liabilities, Finance Leases	us-gaap:OtherLiabilitiesNoncurrent