LEASE ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
ASSETS.
Operating lease assets	$ 135,193	$ 129,894
Operating Lease Assets Balance Sheet Location	us-gaap:OperatingLeaseRightOfUseAsset	us-gaap:OperatingLeaseRightOfUseAsset
Finance lease assets	$ 19,245	$ 18,261
Total leased assets	154,438	148,155
Current
Operating Lease, Liability, Current	$ 37,660	$ 35,535
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Operating Lease, Liability, Current	Operating Lease, Liability, Current
Finance Lease, Liability, Current	$ 7,730	$ 8,770
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Non-current
Operating Lease, Liability, Noncurrent	$ 114,350	$ 112,754
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Operating Lease, Liability, Noncurrent	Operating Lease, Liability, Noncurrent
Finance Lease, Liability, Noncurrent	$ 10,609	$ 10,765
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other liabilities, noncurrent	Other liabilities, noncurrent
Total lease liabilities	$ 170,349	$ 167,824
Finance lease assets [Member]
Current
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Property, plant and equipment, net	Property, plant and equipment, net