Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net income attributable to Stewart	$ 13,999	$ 29,434	$ 21,624	$ 148,991
Denominator (000):
Basic average shares outstanding (in shares)	27,348	27,113	27,269	27,031
Diluted average shares outstanding (in shares)	27,650	27,371	27,445	27,359
Basic earnings per share attributable to Stewart (in usd per share)	$ 0.51	$ 1.09	$ 0.79	$ 5.51
Diluted earnings per share attributable to Stewart (in usd per share)	$ 0.51	$ 1.08	$ 0.79	$ 5.45
Stock options
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted units and shares (in shares)	69	124	52	181
Restricted stock and restricted stock units
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted units and shares (in shares)	233	134	124	147