INVESTMENTS - Commercial Mortgage Loans by Key Credit Quality Indicator (Details) - Commercial mortgage loans $ in Millions	Dec. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 62
2019	656
2018	170
2017	69
2016	763
Total Financing Receivable	$ 1,720
Weighted average debt-service coverage ratio	2.37
2020
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average debt-service coverage ratio	2.00
2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average debt-service coverage ratio	2.52
2018
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average debt-service coverage ratio	2.21
2017
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average debt-service coverage ratio	2.58
2016
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average debt-service coverage ratio	2.27
Loan to Value Ratio, Zero to Fifty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 31
2019	400
2018	100
2017	69
2016	554
Total Financing Receivable	$ 1,154
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	$ 31
2019	223
2018	70
2017	0
2016	161
Total Financing Receivable	$ 485
Weighted average debt-service coverage ratio	1.94
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
Total Financing Receivable	$ 55
Weighted average debt-service coverage ratio	1.76
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
Total Financing Receivable	$ 26
Weighted average debt-service coverage ratio	1.66