Unearned revenue liability (URL Rollforward) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Insurance [Abstract]
Balance – beginning of period	$ 675	$ 608	$ 673	$ 567
Deferred revenue	69	63
Amortization	(36)	(29)
Other (including foreign exchange)	(31)	7
Balance – end of period	$ 675	$ 608	$ 673	$ 567