BUSINESS ACQUISITIONS - Acquired Identifiable Assets and Assumed Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Aug. 06, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 1,419,373		$ 632,469	$ 632,469	$ 631,884	$ 627,392	$ 627,392
BioScrip
Business Acquisition [Line Items]
Accounts receivable, net		$ 97,163
Inventories		19,683
Property and equipment, net		49,697
Intangible assets, net		193,712
Deferred tax assets, net of deferred tax liabilities		26,731
Operating lease right-of-use asset		22,378
Operating lease liability		(28,897)
Accounts payable		(61,420)
Other assumed liabilities, net of other acquired assets		(18,737)
Total acquired identifiable assets and liabilities		300,310
Goodwill		786,904
Total consideration transferred		$ 1,087,214