Shareholders' equity - Reconciliation of basic to diluted weighted average common shares outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Basic (in shares)	46,774	46,488	46,200
Dilutive effect of share based awards (in shares)	653	799	890
Diluted (in shares)	47,427	47,287	47,090