Fair Value - Rollforward of Level 3 assets and liabilities (Details) - Recurring - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2024		Sep. 30, 2023		Sep. 30, 2024	Sep. 30, 2023
Other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		$ (35)		$ (19)		$ (22)	$ (14)
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(1)		0		(1)	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		0	0
Purchases, issuances, sales and settlements
Purchases		0		0		0	0
Issuances		(9)		(4)		(22)	(9)
Sales		0		0		0	0
Settlements		2		2		2	2
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		(43)		(21)		(43)	(21)
Available for sale | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		160		100		147	121
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0		0		0	1
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		(1)		2	(1)
Purchases, issuances, sales and settlements
Purchases		0		25		98	68
Issuances		0		0		0	0
Sales		0		0		0	0
Settlements		(19)		0		(106)	(65)
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		141		124		141	124
Available for sale | Short-term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		97		0		84	0
Total gains or (losses) (realized/unrealized) - included in earnings		0	[1]	0	[1]	0	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		1	0
Purchases, issuances, sales and settlements
Purchases		0		0		12	0
Issuances		0		0		0	0
Sales		0		0		0	0
Settlements		0		0		0	0
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		97		0		97	0
Fair value option | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		144		86		106	33
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0		0		(4)	(1)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		0	0
Purchases, issuances, sales and settlements
Purchases		39		29		99	87
Issuances		0		0		0	0
Sales		(2)		(6)		(4)	(10)
Settlements		(14)		(9)		(30)	(9)
Transfers in and/or out of Level 3		123		0		123	0
Balance at end of period		290		100		290	100
Fair value option | Short term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		14		0		10	0
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0		0		0	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		0	0
Purchases, issuances, sales and settlements
Purchases		5		4		15	4
Issuances		0		0		0	0
Sales		0		0		0	0
Settlements		(4)		0		(10)	0
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		15		4		15	4
Fair value option | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		4		4		4	4
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0		0		0	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		0	0
Purchases, issuances, sales and settlements
Purchases		0		0		0	0
Issuances		0		0		0	0
Sales		0		0		0	0
Settlements		0		0		0	0
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		4		4		4	4
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		6		5		5	4
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0		0		0	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0		0		0	0
Purchases, issuances, sales and settlements
Purchases		0		0		1	1
Issuances		0		0		0	0
Sales		0		0		0	0
Settlements		0		0		0	0
Transfers in and/or out of Level 3		0		0		0	0
Balance at end of period		$ 6		$ 5		$ 6	$ 5

[1] Gains or losses were included in net realized gains (losses).