Unearned revenue liability (URL Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Insurance [Abstract]
Balance – beginning of period	$ 673	$ 567
Deferred revenue	144	134
Amortization	(73)	(67)
Other (including foreign exchange)	(33)	39
Balance – end of period	$ 711	$ 673