INVESTMENTS - Commercial Mortgage Loans by Key Credit Quality Indicators (Details) - Commercial mortgage loans $ in Millions	Sep. 30, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 208
2020	47
2019	646
2018	168
2017	68
Prior	724
Total Financing Receivable	$ 1,861
Weighted Average Debt Service Coverage Ratio	2.42
2021
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.49
2020
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	1.94
2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.55
2018
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.32
2017
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.78
Prior
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.30
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 174
2020	47
2019	559
2018	168
2017	68
Prior	561
Total Financing Receivable	$ 1,577
Weighted Average Debt Service Coverage Ratio	2.51
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 34
2020	0
2019	87
2018	0
2017	0
Prior	138
Total Financing Receivable	$ 259
Weighted Average Debt Service Coverage Ratio	1.97
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 0
2020	0
2019	0
2018	0
2017	0
Prior	25
Total Financing Receivable	$ 25
Weighted Average Debt Service Coverage Ratio	1.67