Investments - Scheduled maturities of available for sale fixed maturities (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2021	Dec. 31, 2020
Fair Value, Fiscal Year Maturity [Abstract]
Fair Value	$ 9,732	$ 9,084
Fair Value Percent, Fiscal Year Maturity [Abstract]
Average life of ABS	3 years 6 months
Average life of MBS	3 years
Fixed maturities
Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less	$ 1,045
After one year through five years	2,553
After five years through ten years	1,002
After ten years	283
Fixed maturities amortized cost, Subtotal	4,883
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	3,715
MBS (average life of approximately 3 years)	874
Amortized Cost	9,472
Fair Value, Fiscal Year Maturity [Abstract]
One year or less	1,059
After one year through five years	2,656
After five years through ten years	1,053
After ten years	293
Fixed maturities fair value, Subtotal	5,061
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	3,743
MBS (average life of approximately 3 years)	928
Fair Value	$ 9,732	$ 9,084
Fair Value Percent, Fiscal Year Maturity [Abstract]
One year or less	11.00%
After one year through five years	27.00%
After five years through ten years	11.00%
After ten years	3.00%
Fixed maturities fair value, Subtotal, Percent	52.00%
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	38.00%
MBS (average life of approximately 3 years)	10.00%
Fair value, Total, Percent	100.00%

Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent.

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Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value, Percent.

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Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value, Percent.

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Available for sale securities debt maturities excluding ABS and MBS amortized cost.

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Available for sale securities debt maturities excluding ABS and MBS fair value.

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Available-for-sale Securities, Debt Maturities, Fair Value, Total, Percent.

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Available For Sale Securities, Debt Maturities, Fair Value Percent, Fiscal Year Maturity [Abstract]

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Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent.

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Mortgage-backed securities, amortized cost.

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Mortgage-backed securities, fair value, percent.

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Collateralized loan obligations and Other asset-backed securities average useful life.

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Collateralized loan obligations and Other asset-backed securities, amortized cost.

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Collateralized loan obligations and other Asset-backed securities, fair value.

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Collateralized loan obligations and other Asset-backed securities, fair value, percent.

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Mortgage backed securities average useful life.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as available-for-sale.

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