BENEFITS PAYABLE - Narrative (Detail) claim in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) claim	Dec. 31, 2017 USD ($) claim	Dec. 31, 2016 USD ($) claim
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Favorable Medical Claims Reserve Development | $	$ 503	$ 483	$ 582
Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	2,900
Group and Specialty
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	448
Individual Commercial
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	$ 1
2018 Claims Incurred Year | Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date	104.3
2018 Claims Incurred Year | Group and Specialty
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date	10.4
2017 Claims Incurred Year | Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date		102.1
2017 Claims Incurred Year | Group and Specialty
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date		11.1
2017 Claims Incurred Year | Individual Commercial
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date		2.2
2016 Claims Incurred Year | Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date			96.2
2016 Claims Incurred Year | Group and Specialty
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date			12.9
2016 Claims Incurred Year | Individual Commercial
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date			9.5