Investments - Loans Segregated By Risk Rating (Details) $ in Millions	Jun. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total non-accrual loans	$ 39
Residential Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2020	304
2019	704
2018	78
2017	48
2016	65
Prior	2
Financing Receivable, before Allowance for Credit Loss, Total	1,201
Total non-accrual loans	39
Residential Portfolio Segment | Current (less than 30 days past due)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	231
2019	408
2018	51
2017	47
2016	62
Prior	2
Financing Receivable, before Allowance for Credit Loss, Total	801
Residential Portfolio Segment | 30-89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2020	72
2019	241
2018	25
2017	1
2016	2
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	341
Residential Portfolio Segment | Over 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	55
2018	2
2017	0
2016	1
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	59
Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2020	163
2019	0
2018	6
2017	0
2016	11
Prior	396
Financing Receivable, before Allowance for Credit Loss, Total	576
Total non-accrual loans	0
Commercial Portfolio Segment | Greater than 1.25
Financing Receivable, Credit Quality Indicator [Line Items]
2020	144
2019	0
2018	6
2017	0
2016	11
Prior	389
Financing Receivable, before Allowance for Credit Loss, Total	550
Commercial Portfolio Segment | Greater than 1.00 but less than 1.25
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19
2019	0
2018	0
2017	0
2016	0
Prior	7
Financing Receivable, before Allowance for Credit Loss, Total	26
Commercial Portfolio Segment | Less than 1.00
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	0
Commercial Portfolio Segment | Less than 50%
Financing Receivable, Credit Quality Indicator [Line Items]
2020	96
2019	0
2018	6
2017	0
2016	0
Prior	339
Financing Receivable, before Allowance for Credit Loss, Total	441
Commercial Portfolio Segment | LTV 50 to 60 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	34
2019	0
2018	0
2017	0
2016	11
Prior	57
Financing Receivable, before Allowance for Credit Loss, Total	102
Commercial Portfolio Segment | LTV 60 to 75 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33
2019	0
2018	0
2017	0
2016	0
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	33
Commercial Portfolio Segment | Current (less than 30 days past due)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	163
2019	0
2018	6
2017	0
2016	11
Prior	396
Financing Receivable, before Allowance for Credit Loss, Total	576
Commercial Portfolio Segment | 30-89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	0
Commercial Portfolio Segment | Over 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Financing Receivable, before Allowance for Credit Loss, Total	$ 0