INVESTMENTS - Commercial Mortgage Loans by Key Credit Quality Indicators (Details) - Commercial mortgage loans $ in Millions	Sep. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 48
2019	659
2018	171
2017	69
2016	785
Prior	0
Total Financing Receivable	$ 1,732
Weighted Average Debt Service Coverage Ratio	2.39
2020
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	1.98
2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.53
2018
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.23
2017
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.56
2016
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.32
Prior
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	0.00
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 32
2019	402
2018	101
2017	69
2016	553
Prior	0
Total Financing Receivable	$ 1,157
Weighted Average Debt Service Coverage Ratio	2.63
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 16
2019	224
2018	70
2017	0
2016	184
Prior	0
Total Financing Receivable	$ 494
Weighted Average Debt Service Coverage Ratio	1.93
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 0
2019	33
2018	0
2017	0
2016	22
Prior	0
Total Financing Receivable	$ 55
Weighted Average Debt Service Coverage Ratio	1.79
Loan-to-Value Ratio Eighty Percent and Above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 0
2019	0
2018	0
2017	0
2016	26
Prior	0
Total Financing Receivable	$ 26
Weighted Average Debt Service Coverage Ratio	1.66

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Amount of financing receivable originated in current fiscal year.

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Amount of financing receivable originated in fiscal year prior to current fiscal year.

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