Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income attributable to Stewart	$ 66,108	$ 17,553	$ 78,648	$ 36,151
Denominator (000):
Basic average shares outstanding	23,616	23,556	23,608	23,537
Average number of dilutive shares relating to grants of restricted shares and units	157	143	172	140
Basic and diluted average shares outstanding	23,773	23,699	23,780	23,677
Basic earnings per share attribute to Stewart (in usd per share)	$ 2.80	$ 0.75	$ 3.33	$ 1.54
Diluted earnings per share attribute to Stewart (in usd per share)	$ 2.78	$ 0.74	$ 3.31	$ 1.53