BASIS OF PRESENTATION - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill	$ 825,511	$ 825,511	$ 793,470
Deferred tax liability	839,316	839,316	1,232,407
Deferred income tax expense		(14,904)	$ (697,727)	$ 247,687
Restatement Adjustment | Adjustment Pertaining To Tax Deductibility Following Dai-ichi Acquisition
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill	32,000	32,000
Deferred tax liability	21,300	$ 21,300
Deferred income tax expense	$ 10,700