Unearned revenue liability (URL Rollforward) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Insurance [Abstract]
Balance – beginning of period	$ 711	$ 673
Deferred revenue	69	69
Amortization	(38)	(36)
Other (including foreign exchange)	11	(31)
Balance – end of period	$ 753	$ 675