BUSINESS SEGMENT INFORMATION - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 222,424	$ 225,985
Operating Segments | Individual Retirement
Segment Reporting Information [Line Items]
Total assets	108,741	120,612
Operating Segments | Group Retirement
Segment Reporting Information [Line Items]
Total assets	42,731	40,472
Operating Segments | Investment Management and Research
Segment Reporting Information [Line Items]
Total assets	11,345	10,079
Operating Segments | Protection Solutions
Segment Reporting Information [Line Items]
Total assets	38,897	34,328
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	$ 20,710	$ 20,494