SIGNIFICANT ACCOUNTING POLICIES - New Accounting Pronouncements (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' equity	$ 15,166	$ 18,881		$ 11,658	$ 13,932	$ 12,370	$ 12,428
Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' equity	$ 2,658	$ 7,953		2,242	$ 4,532	$ 4,268	$ 5,098
Cumulative effect of period of adoption, adjusted balance
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' equity				(32)
Cumulative effect of period of adoption, adjusted balance | Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' equity				$ (32)
Accounting Standards Update 2016-13 | Cumulative effect of period of adoption, adjusted balance | Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' equity			$ (40)