INVESTMENTS - Commercial Mortgage Loans by Key Credit Quality Indicators (Details) - Commercial mortgage loans	Mar. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 39
2019	664
2018	172
2017	69
2016	796
Prior	0
Total Financing Receivable	$ 1,740
Weighted Average Debt Service Coverage Ratio	2.29
2020
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	1.84
2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.33
2018
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.16
2017
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.37
2016
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted Average Debt Service Coverage Ratio	2.30
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	$ 12
2019	474
2018	156
2017	69
2016	683
Prior	0
Total Financing Receivable	$ 1,394
Weighted Average Debt Service Coverage Ratio	2.43
Loan to Value Ratio, Sixty to Sixty-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 27
2019	190
2018	16
2017	0
2016	90
Prior	0
Total Financing Receivable	$ 323
Weighted Average Debt Service Coverage Ratio	1.74
Loan to Value Ratio, Seventy to Seventy-nine Point Nine-nine Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 0
2019	0
2018	0
2017	0
2016	23
Prior	0
Total Financing Receivable	$ 23
Weighted Average Debt Service Coverage Ratio	1.32