INVESTMENTS - Middle Market Loans by Key Credit Quality Indicators (Details) - Middle market loans $ in Millions	Sep. 30, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 757
2020	945
2019	1,033
2018	620
2017	375
Prior	200
Revolving Loans	551
Total Financing Receivable	4,481
BBB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	54
2020	78
2019	51
2018	39
2017	10
Prior	3
Revolving Loans	68
Total Financing Receivable	303
BB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	346
2020	347
2019	283
2018	163
2017	106
Prior	27
Revolving Loans	221
Total Financing Receivable	1,493
B Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	357
2020	493
2019	635
2018	323
2017	154
Prior	121
Revolving Loans	170
Total Financing Receivable	2,253
CCC Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	19
2019	64
2018	81
2017	79
Prior	49
Revolving Loans	87
Total Financing Receivable	379
CC Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0
2019	0
2018	14
2017	26
Prior	0
Revolving Loans	5
Total Financing Receivable	45
C and Lower Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	8
2019	0
2018	0
2017	0
Prior	0
Revolving Loans	0
Total Financing Receivable	$ 8