Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net income attributable to Stewart	$ 10,944	$ 26,375	$ 33,601	$ 38,778
Less: Cash paid on Class B Common Shares conversion	0	0	0	(12,000)
Net income available to common shareholders	$ 10,944	$ 26,375	$ 33,601	$ 26,778
Denominator (000):
Basic average shares outstanding	23,448	23,371	23,442	23,362
Diluted average shares outstanding	23,564	23,611	23,571	23,596
Basic earnings per share attributable to Stewart (in usd per share)	$ 0.47	$ 1.13	$ 1.43	$ 1.15
Diluted earnings per share attributable to Stewart (in usd per share)	$ 0.46	$ 1.12	$ 1.43	$ 1.13
Options
Denominator (000):
Average number of dilutive shares relating to share-based incentives	0	1	0	1
Restricted Shares
Denominator (000):
Average number of dilutive shares relating to share-based incentives	116	239	129	233