Unearned revenue liability (URL Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Insurance [Abstract]
Balance – beginning of period	$ 758	$ 711
Deferred revenue	30	34
Amortization	(20)	(18)
Other (including foreign exchange)	(6)	(8)
Balance – end of period	$ 762	$ 719