INVESTMENTS - Middle Market Loans by Key Credit Quality Indicators (Details) - Middle market loans	Mar. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 305
2019	1,220
2018	715
2017	523
2016	191
Prior	84
Revolving Loans	454
Total Financing Receivable	3,492
BBB
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9
2019	57
2018	52
2017	22
2016	12
Prior	0
Revolving Loans	15
Total Financing Receivable	167
BB
Financing Receivable, Credit Quality Indicator [Line Items]
2020	86
2019	277
2018	187
2017	140
2016	56
Prior	20
Revolving Loans	84
Total Financing Receivable	850
B
Financing Receivable, Credit Quality Indicator [Line Items]
2020	210
2019	827
2018	466
2017	309
2016	98
Prior	58
Revolving Loans	338
Total Financing Receivable	2,306
CCC
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	58
2018	10
2017	34
2016	25
Prior	4
Revolving Loans	15
Total Financing Receivable	146
CC Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1
2018	0
2017	18
2016	0
Prior	2
Revolving Loans	2
Total Financing Receivable	$ 23