Postretirement benefits (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
	Oct. 31, 2016	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Expenses recognized during period under the defined contributions plans		$ 230	$ 214	$ 211
Defined Benefit Plan, Plan Amendment [Abstract]
Other Investments		13,696	11,169
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation		3,400	4,800
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		38
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		81	119	120
Actuarial Loss (gain)		(4)	(10)
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation		18	20
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		1
Defined Benefit Plan, Plan Amendment [Abstract]
(Increase) decrease in other comprehensive income, curtailment		0	0	0
Amortization of Prior Service Cost (Credit)		$ 0	26	83
Defined Benefit Plan, Equity Securities [Member] | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage		55.00%
Defined Benefit Plan, Equity Securities [Member] | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage		65.00%
Level 2 | Fixed Maturities [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 50
Other Investments
Defined Benefit Plan, Plan Amendment [Abstract]
Other Investments		47	51
Other Investments | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		31
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		3,316	4,151	3,739
Actuarial Loss (gain)		(890)	(161)
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation		66	73
Defined Benefit Plan, Plan Amendment [Abstract]
(Increase) decrease in other comprehensive income, curtailment		0	0	0
Amortization of Prior Service Cost (Credit)		0	0	0
UNITED STATES | Postretirement Health Coverage [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation	$ 383
Amortization of Prior Service Cost (Credit)			26	79
UNITED STATES | Postretirement Health Coverage [Member] | Subject to Amortization [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation	$ 410
UNITED STATES | Other Investments | Pension Plan [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Other Investments		538	542
Non - U.S. | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		938	1,318	1,284
Actuarial Loss (gain)		(391)	(47)
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation		61	380
Defined Benefit Plan, Plan Amendment [Abstract]
(Increase) decrease in other comprehensive income, curtailment		0	0	(1)
Amortization of Prior Service Cost (Credit)		0	0	$ 0
Non - U.S. | Other Investments | Pension Plan [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Other Investments		$ 201	$ 175