Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator (in $ thousands):
Net income attributable to Stewart	$ 30,439	$ 162,305	$ 323,216
Denominator (in thousands):
Basic average shares outstanding (in shares)	27,293	27,055	26,822
Diluted average shares outstanding (in shares)	27,520	27,347	27,168
Basic earnings per share attributable to Stewart (in usd per share)	$ 1.12	$ 6.00	$ 12.05
Diluted earnings per share attributable to Stewart (in usd per share)	$ 1.11	$ 5.94	$ 11.90
Stock options
Denominator (in thousands):
Average number of dilutive shares relating to restricted shares and units (in shares)	69	159	197
Restricted stock and restricted stock units
Denominator (in thousands):
Average number of dilutive shares relating to restricted shares and units (in shares)	158	133	149