Employee plans - Company's Investment Policy Targets and Ranges for Each Asset Category (Details) - Pension Plans	Dec. 31, 2021
U.S. Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	52.00%
U.S. Plans | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	34.00%
U.S. Plans | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	0.00%
U.S. Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	14.00%
U.S. Plans | Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	47.00%
U.S. Plans | Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	29.00%
U.S. Plans | Minimum | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	0.00%
U.S. Plans | Minimum | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	9.00%
U.S. Plans | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	57.00%
U.S. Plans | Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	39.00%
U.S. Plans | Maximum | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	5.00%
U.S. Plans | Maximum | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	19.00%
International Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	18.00%
International Plans | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	62.00%
International Plans | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	0.00%
International Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	20.00%
International Plans | Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	15.00%
International Plans | Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	57.00%
International Plans | Minimum | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	0.00%
International Plans | Minimum | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	17.00%
International Plans | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	20.00%
International Plans | Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	66.00%
International Plans | Maximum | Cash
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	5.00%
International Plans | Maximum | Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan target allocation as proportion of assets (as a percent)	24.00%