INVESTMENTS - Commercial Mortgage Loans by Key Credit Quality Indicators (Details) - Commercial mortgage loans $ in Millions	Jun. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 48
2019	661
2018	171
2017	69
2016	791
Prior	0
Total Financing Receivable	$ 1,740
Weighted Average Debt Service Coverage Ratio	2.37
2020
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	1.91
2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.50
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	2.59
2016
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.31
Prior
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	0
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 32
2019	404
2018	101
2017	69
2016	594
Prior	0
Total Financing Receivable	$ 1,200
Weighted Average Debt Service Coverage Ratio	2.59
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	148
Prior	0
Total Financing Receivable	$ 458
Weighted Average Debt Service Coverage Ratio	1.92
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	23
Prior	0
Total Financing Receivable	$ 56
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	1.63