Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Net income attributable to Stewart	$ 15,815	$ 61,660	$ 7,625	$ 119,557
Denominator (000):
Basic average shares outstanding (in shares)	27,255	27,018	27,228	26,989
Diluted average shares outstanding (in shares)	27,444	27,293	27,402	27,377
Basic earnings per share attributable to Stewart (in usd per share)	$ 0.58	$ 2.28	$ 0.28	$ 4.43
Diluted earnings per share attributable to Stewart (in usd per share)	$ 0.58	$ 2.26	$ 0.28	$ 4.37
Stock options
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted shares and units (in shares)	43	154	52	226
Restricted stock and restricted stock units
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted shares and units (in shares)	146	121	122	162