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Investments - Available for sale fixed maturities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	$ 45,670			$ 44,524
Fixed maturities, available for sale, allowance for expected credit losses	61	$ 61		0
Available for sale (AFS) fixed maturities	48,046			46,505
Total fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	45,670			44,524
Fixed maturities, available for sale, allowance for expected credit losses	61			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	2,894			2,069
Fixed maturities, Available for sale, Gross Unrealized, Losses	(457)			(88)
Available for sale (AFS) fixed maturities	48,046			46,505
Total fixed maturities \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	2,437			1,981
U.S. Government and government agencies
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	196			199
Fixed maturities, available for sale, allowance for expected credit losses	0			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	14			10
Fixed maturities, Available for sale, Gross Unrealized, Losses	0			0
Available for sale (AFS) fixed maturities	210			209
U.S. Government and government agencies \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	14			10
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	6,373			6,604
Fixed maturities, available for sale, allowance for expected credit losses	0			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	581			363
Fixed maturities, Available for sale, Gross Unrealized, Losses	(3)			(4)
Available for sale (AFS) fixed maturities	6,951			6,963
States, municipalities and political subdivisions \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	578			359
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	176			170
Fixed maturities, available for sale, allowance for expected credit losses	0			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	8			3
Fixed maturities, Available for sale, Gross Unrealized, Losses	0			(1)
Available for sale (AFS) fixed maturities	184			172
Foreign government \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	8			2
Residential MBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	3,000			2,900
Fixed maturities, available for sale, allowance for expected credit losses	5			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	239			265
Fixed maturities, Available for sale, Gross Unrealized, Losses	(12)			(5)
Available for sale (AFS) fixed maturities	3,222			3,160
Residential MBS \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	227			260
Commercial MBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	852			896
Fixed maturities, available for sale, allowance for expected credit losses	0			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	39			31
Fixed maturities, Available for sale, Gross Unrealized, Losses	(2)			0
Available for sale (AFS) fixed maturities	889			927
Commercial MBS \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	37			31
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	4,625			4,307
Fixed maturities, available for sale, allowance for expected credit losses	20			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	16			10
Fixed maturities, Available for sale, Gross Unrealized, Losses	(114)			(37)
Collateralized loan obligations \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	(98)			(27)
Other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	7,400			6,992
Fixed maturities, available for sale, allowance for expected credit losses	14			0
Fixed maturities, Available for sale, Gross Unrealized, Gains	118			156
Fixed maturities, Available for sale, Gross Unrealized, Losses	(189)			(20)
Available for sale (AFS) fixed maturities	7,315			7,128
Other asset-backed securities \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	(71)			136
Corporate and other
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	23,048			22,456
Fixed maturities, available for sale, allowance for expected credit losses	22	$ 24	$ 0	0
Fixed maturities, Available for sale, Gross Unrealized, Gains	1,879			1,231
Fixed maturities, Available for sale, Gross Unrealized, Losses	(137)			(21)
Available for sale (AFS) fixed maturities	24,768			23,666
Corporate and other \| Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	1,742			1,210
Managed by third parties \| Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Available for sale (AFS) fixed maturities	$ 4,507			$ 4,280