BUSINESS SEGMENT INFORMATION - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total assets	$ 240,781	$ 249,870
Operating Segments | Individual Retirement
Segment Reporting Information [Line Items]
Total assets	117,299	123,626
Operating Segments | Group Retirement
Segment Reporting Information [Line Items]
Total assets	41,194	43,588
Operating Segments | Investment Management and Research
Segment Reporting Information [Line Items]
Total assets	11,915	10,170
Operating Segments | Protection Solutions
Segment Reporting Information [Line Items]
Total assets	45,266	46,886
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	$ 25,107	$ 25,600