SIGNIFICANT ACCOUNTING POLICIES - ACCOUNTING CHANGE AND ADOPTION OF NEW ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	$ 9,010	$ 7,476	$ 7,479	$ 5,978	$ 6,150
Difference Between Revenue Guidance In Effect Before And After Topic 606 | Accounting Standards Update 2014-09 | Pro Forma
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	35
Equity
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Available-for-sale securities	$ 157