REINSURANCE - Balance and Financial Rating Related to Reinsurers (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 824	$ 822
Munich American Reassurance Company
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 259
A.M. Best Rating	A+ (superior)
Protective Life Insurance Company
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 181
A.M. Best Rating	A+ (superior)
Westport Insurance Corporation, a Swiss Re Corporation subsidiary
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 134
A.M. Best Rating	A+ (superior)
General Re Life Corporation, a Berkshire Hathaway subsidiary
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 133
A.M. Best Rating	A++ (superior)
All others
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Total Recoverable	$ 117
A.M. Best Rating	A+ to A- (superior to excellent)