INVESTMENTS - Middle Market Loans by Key Credit Quality Indicators (Details) - Middle market loans $ in Millions	Sep. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 508
2019	1,190
2018	754
2017	510
2016	201
Prior	70
Revolving Loans	378
Total Financing Receivable	3,611
BBB
Financing Receivable, Credit Quality Indicator [Line Items]
2020	25
2019	117
2018	62
2017	56
2016	5
Prior	0
Revolving Loans	16
Total Financing Receivable	281
BB
Financing Receivable, Credit Quality Indicator [Line Items]
2020	201
2019	235
2018	237
2017	84
2016	37
Prior	15
Revolving Loans	86
Total Financing Receivable	895
B
Financing Receivable, Credit Quality Indicator [Line Items]
2020	267
2019	740
2018	315
2017	235
2016	119
Prior	24
Revolving Loans	185
Total Financing Receivable	1,885
CCC
Financing Receivable, Credit Quality Indicator [Line Items]
2020	15
2019	98
2018	121
2017	96
2016	37
Prior	31
Revolving Loans	90
Total Financing Receivable	488
CC Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	19
2017	39
2016	3
Prior	0
Revolving Loans	1
Total Financing Receivable	$ 62