Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income attributable to Stewart	$ 54,236	$ 5,177
Denominator
Basic average shares outstanding (in shares)	26,736	23,638
Average number of dilutive shares relating to options (in shares)	103	0
Average number of dilutive shares relating to grants of restricted units and shares (in shares)	145	111
Diluted average shares outstanding (in shares)	26,984	23,749
Basic earnings per share attributable to Stewart (in usd per share)	$ 2.03	$ 0.22
Diluted earnings per share attributable to Stewart (in usd per share)	$ 2.01	$ 0.22