Shareholders' equity - Schedule of Nonvested Performance-based Units Activity (Details) - Performance Share Awards - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested at beginning of year (in shares)	1,015,433,000	1,142,879,000	698,482,000
Granted (in shares)	484,781,000	553,090,000	673,127,000
Settled (in shares)	(503,844,000)	(646,635,000)	(151,511,000)
Canceled (in shares)	(10,266,000)	(33,901,000)	(77,219,000)
Unvested at end of year (in shares)	986,104,000	1,015,433,000	1,142,879,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested at beginning of year (in dollars per share)	$ 15.04	$ 12.87	$ 12.26
Granted (in dollars per share)	21.80	17.48	13.47
Settled (in dollars per share)	15.26	13.22	13.40
Canceled (in dollars per share)	17.09	14.20	12.50
Unvested at end of year (in dollars per share)	$ 18.18	$ 15.04	$ 12.87