BENEFITS PAYABLE - Narrative (Detail) claim in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) claim	Dec. 31, 2016 USD ($) claim	Dec. 31, 2015 USD ($) claim
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Favorable Medical Claims Reserve Development | $	$ 483	$ 582	$ 236
Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	2,500
Group and Specialty
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	500
Individual Commercial
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total IBNR | $	$ 85
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	97.8
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	10.6
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		96.0
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		12.8
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
2015 Claims Incurred Year | Retail
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cumulative Number of Reported Claims - Service Date			93.9
2015 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			13.4
2015 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			11.0