ORGANIZATION AND BASIS OF PRESENTATION (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) segment	Mar. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
Summary of significant accounting policies
Number of reporting segments | segment	2
Right-to-use assets			$ 42,100
Lease obligation liabilities			45,500
Lease obligation liabilities, other current	$ 0	$ 15,098	16,700
Lease obligation liabilities, other noncurrent	0	23,202	28,800
Reduction accrued rent and lease incentives, effect of adopting accounting standard			$ 3,400
Lenders One
Summary of significant accounting policies
Total assets	2,700	2,000
Total liabilities	$ 1,300	$ 900