INSURANCE LIABILITIES - Variable Annuity Contracts with GMDB and GMIB Features and Buybacks (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Net Amount at Risk by Product and Guarantee [Line Items]
Separate Accounts		$ 62,286	$ 57,848
Option to elect a partial buyout of rider, percentage	(50.00%)
Loss from impact of buyback	$ 4
GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		14,194
Separate Accounts		94,672	$ 86,890
Net amount at risk, gross		17,527
Net amount at risk, net of amounts reinsured		$ 7,846
Average attained age of contractholders (in years)		55 years 1 month 6 days
Percentage of contractholders’ over age 70		18.10%
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.50%
GMIB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 316
Separate Accounts		62,286
Net amount at risk, gross		7,254
Net amount at risk, net of amounts reinsured		$ 1,848
Weighted average years remaining until annuitization (in years)		9 months 18 days
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.50%
Return of Premium | GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 13,820
Separate Accounts		45,816
Net amount at risk, gross		169
Net amount at risk, net of amounts reinsured		$ 169
Average attained age of contractholders (in years)		51 years 3 months 18 days
Percentage of contractholders’ over age 70		9.60%
Ratchet | GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 109
Separate Accounts		9,556
Net amount at risk, gross		57
Net amount at risk, net of amounts reinsured		$ 39
Average attained age of contractholders (in years)		66 years 3 months 18 days
Percentage of contractholders’ over age 70		40.20%
Roll-Up | GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 65
Separate Accounts		3,516
Net amount at risk, gross		1,961
Net amount at risk, net of amounts reinsured		$ 1,344
Average attained age of contractholders (in years)		72 years 10 months 24 days
Percentage of contractholders’ over age 70		63.10%
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.00%
Roll-Up | GMIB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 23
Separate Accounts		21,195
Net amount at risk, gross		917
Net amount at risk, net of amounts reinsured		$ 287
Weighted average years remaining until annuitization (in years)		1 year 7 months 6 days
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.00%
Combo | GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 200
Separate Accounts		35,784
Net amount at risk, gross		15,340
Net amount at risk, net of amounts reinsured		$ 6,294
Average attained age of contractholders (in years)		68 years 2 months 12 days
Percentage of contractholders’ over age 70		46.50%
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.50%
Combo | GMIB
Net Amount at Risk by Product and Guarantee [Line Items]
General Account		$ 293
Separate Accounts		41,091
Net amount at risk, gross		6,337
Net amount at risk, net of amounts reinsured		$ 1,561
Weighted average years remaining until annuitization (in years)		8 months 12 days
Range of contractually specified interest rates (as a percent), minimum		3.00%
Range of contractually specified interest rates (as a percent), maximum		6.50%