Investments Investments (held-to-maturity credit quality indicator) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 11,896	$ 12,581
Fixed Maturities Percent of Total Amortized cost	100.00%
Standard & Poor's, AAA Rating [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 2,583
Fixed Maturities Percent of Total Amortized cost	22.00%
Standard & Poor's, AA Rating [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 6,397
Fixed Maturities Percent of Total Amortized cost	54.00%
Standard & Poor's, A Rating [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 2,302
Fixed Maturities Percent of Total Amortized cost	19.00%
Standard & Poor's, BBB Rating [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 591
Fixed Maturities Percent of Total Amortized cost	5.00%
Standard & Poor's, BB Rating [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 21
Fixed Maturities Percent of Total Amortized cost	0.00%
Other [Member]
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Debt Securities, Held-to-maturity	$ 2
Fixed Maturities Percent of Total Amortized cost	0.00%