INCOME TAXES - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended					6 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Valuation allowance			$ 310					$ 420	$ 310
Net asset basis step-up								863
Swiss tax reform net asset basis step-up			0					159	0
Deferred tax asset, swiss tax reform net asset basis step-up, valuation allowance								69
Deferred tax asset, swiss tax reform net asset basis step-up, net								90
Deferred tax benefit recognized due to reduced U.S tax rate and other effects of tax act								19	8	$ 283
Provisional charge recognized for one-time transitional tax expense								(16)	(5)	529
U.S. Valuation allowance recognized in respect of foreign tax credit DTA								0	194	(339)
Unrecognized interest and penalties expense								21	22
Unrecognized tax benefits that, if recognized, would impact effective tax rate			84					70	84	88
Gross unrecognized tax benefit liability			68					62	68
Net indemnification receivables			6					6	6	13
Expected reduction in gross unrecognized tax benefits								27
One Time transitional Tax Expense								192		5
Income tax expense (benefit)	$ 13	$ 44	102	$ 63	$ 46	$ 57	$ 109	(41)	65	491
Deferred Tax Assets, Net of Valuation Allowance			1,001					1,287	1,001
Deferred Tax Assets, Net			268					429	268
Transition tax due to 2017 Tax Act								(16)	(5)	529
Tax Cuts and Jobs Act, Change in Tax Rate, Income Tax Expense (Benefit), Would Be Incurred If Earnings Remitted								19
Increase (Decrease) Due To Notional Interest Deduction								$ 57
Maximum
Income Taxes [Line Items]
U.S statutory tax rate, percent								35.00%
Minimum
Income Taxes [Line Items]
U.S statutory tax rate, percent								21.00%
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carryforwards								$ 1,100
Domestic Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards								58
Tax credit carryforwards								410
Foreign Tax Credit Carryforward, Amount								395
Foreign Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards								1,300
Tax credit carryforwards								49
Valuation allowance			$ 175					180	175	$ 339
Income tax expense (benefit)									$ (194)
Deferred Tax Assets, Net of Valuation Allowance								90
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount								5
Deferred Tax Assets, Net								$ 24
Impact on earnings from continuing operations per diluted shares								$ 0.27	$ 0.29	$ 0.25
Foreign Tax Authority | Tax Year No Expiration
Income Taxes [Line Items]
Operating loss carryforwards								$ 814
Tax credit carryforwards								$ 48