Investments - Scheduled maturities of available for sale fixed maturities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Fair Value Percent, Fiscal Year Maturity [Abstract]
Average life of ABS	4 years 6 months
Average life of MBS	3 years 6 months
Fixed maturities
Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less	$ 2,018	[1]
After one year through five years	10,563	[1]
After five years through ten years	14,450	[1]
After ten years	3,551	[1]
Fixed maturities amortized cost, Subtotal	30,582	[1]
Collateralized loan obligations and other ABS (average life of approximately 4-1/2 years)	11,494	[1]
MBS (average life of approximately 3-1/2 years)	3,964	[1]
Amortized Cost	46,040	[1]
Fair Value, Fiscal Year Maturity [Abstract]
One year or less	2,027
After one year through five years	10,710
After five years through ten years	14,722
After ten years	3,741
Fixed maturities fair value, Subtotal	31,200
Collateralized loan obligations and other ABS (average life of approximately 4-1/2 years)	10,896
MBS (average life of approximately 3-1/2 years)	4,038
Fair Value	$ 46,134
Fair Value Percent, Fiscal Year Maturity [Abstract]
One year or less	4.00%
After one year through five years	23.00%
After five years through ten years	32.00%
After ten years	8.00%
Fixed maturities fair value, Subtotal, Percent	67.00%
Collateralized loan obligations and other ABS (average life of approximately 4-1/2 years)	24.00%
MBS (average life of approximately 3-1/2 years)	9.00%
Fair value, Total, Percent	100.00%

[1] Amortized cost, net of allowance for expected credit losses.