Investments - Scheduled maturities of available for sale fixed maturities (Details) $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
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	$ 974
After one year through five years	2,456
After five years through ten years	1,126
After ten years	291
Fixed maturities amortized cost, Subtotal	4,847
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	3,300
MBS (average life of approximately 3 years)	902
Amortized Cost	9,049
Fair Value, Fiscal Year Maturity [Abstract]
One year or less	986
After one year through five years	2,553
After five years through ten years	1,174
After ten years	301
Fixed maturities fair value, Subtotal	5,014
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	3,319
MBS (average life of approximately 3 years)	956
Fair Value	$ 9,289
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	13.00%
After ten years	3.00%
Fixed maturities fair value, Subtotal, Percent	54.00%
Collateralized loan obligations and other ABS (average life of approximately 3-1/2 years)	36.00%
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 excluding ABS and MBS fair value percent.

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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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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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

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