LEASES - Schedule of estimated minimum future finance lease obligations (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating Leases
Fiscal year ending December 31, 2019	$ 12,160
Fiscal year ending December 31, 2020	12,845
Fiscal year ending December 31, 2021	10,394
Fiscal year ending December 31, 2022	8,236
Fiscal year ending December 31, 2023	6,488
Thereafter	65,269
Total lease payments	115,392
Less: interest expense	(37,768)
Lease liability balance	77,624
Finance Leases
Fiscal year ending December 31, 2019	2,257
Fiscal year ending December 31, 2020	3,171
Fiscal year ending December 31, 2021	2,634
Fiscal year ending December 31, 2022	2,039
Fiscal year ending December 31, 2023	1,871
Thereafter	4,816
Total lease payments	16,788
Less: interest expense	(3,284)
Lease liability balance	$ 13,504