Investments - Scheduled maturities of available for sale fixed maturities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Percent, Fiscal Year Maturity [Abstract]
Average life of ABS	4 years 6 months
Average life of MBS	4 years 6 months
Securities With Non-Credit Other Than Temporary Impairment Charges [Member]
Fair Value Percent, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ (4)	$ (4)
Fixed maturities
Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less	1,310
After one year through five years	8,521
After five years through ten years	14,235
After ten years	4,609
Fixed maturities amortized cost, Subtotal	28,675
ABS (average life of approximately 4.5 years)	9,781
MBS (average life of approximately 4.5 years)	3,381
Amortized Cost	41,837
Fair Value, Fiscal Year Maturity [Abstract]
One year or less	1,318
After one year through five years	8,554
After five years through ten years	14,044
After ten years	4,606
Fixed maturities fair value, Subtotal	28,522
ABS (average life of approximately 4.5 years)	9,811
MBS (average life of approximately 4.5 years)	3,664
Fair Value	$ 41,997
Fair Value Percent, Fiscal Year Maturity [Abstract]
One year or less	3.00%
After one year through five years	20.00%
After five years through ten years	34.00%
After ten years	11.00%
Fixed maturities fair value, Subtotal, Percent	68.00%
ABS (average life of approximately 4.5 years)	23.00%
MBS (average life of approximately 4.5 years)	9.00%
Fair value, Total, Percent	100.00%