BUSINESS SEGMENT INFORMATION - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total assets	$ 254,110	$ 249,870
Operating Segments | Individual Retirement
Segment Reporting Information [Line Items]
Total assets	125,169	123,626
Operating Segments | Group Retirement
Segment Reporting Information [Line Items]
Total assets	44,895	43,588
Operating Segments | Investment Management and Research
Segment Reporting Information [Line Items]
Total assets	10,812	10,170
Operating Segments | Protection Solutions
Segment Reporting Information [Line Items]
Total assets	45,762	46,886
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	$ 27,472	$ 25,600