GOODWILL AND OTHER INTANGIBLE ASSETS - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill
Goodwill, Gross as of beginning of the year	$ 766,709	$ 764,310
Goodwill, Accumulated Impairment	(567,967)	(567,967)	$ (567,967)
Goodwill, Net as of beginning of the year	198,742	196,343
Additions from acquisitions	27,890	2,399
Goodwill, Gross as of end of the year	794,599	766,709
Goodwill, Net as of end of the year	226,632	198,742
Patient Care
Goodwill
Goodwill, Gross as of beginning of the year	627,410	625,011
Goodwill, Accumulated Impairment	(428,668)	(428,668)	(428,668)
Goodwill, Net as of beginning of the year	198,742	196,343
Additions from acquisitions	27,890	2,399
Goodwill, Gross as of end of the year	655,300	627,410
Goodwill, Net as of end of the year	226,632	198,742
Products & Services
Goodwill
Goodwill, Gross as of beginning of the year	139,299	139,299
Goodwill, Accumulated Impairment	(139,299)	(139,299)	$ (139,299)
Goodwill, Gross as of end of the year	$ 139,299	$ 139,299