Earnings per share - Calculation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income attributable to Stewart	$ 23,599	$ 17,106	$ 12,404	$ 4,658
Less: Cash paid on Class B Common Shares conversion	(12,000)	0	(12,000)	0
Net income available to common shareholders	$ 11,599	$ 17,106	$ 404	$ 4,658
Denominator (000):
Basic average shares outstanding	23,365	23,624	23,357	23,806
Diluted average shares outstanding	23,559	23,795	23,542	23,975
Basic earnings per share attributable to Stewart (in usd per share)	$ 0.50	$ 0.72	$ 0.02	$ 0.20
Diluted earnings per share attributable to Stewart (in usd per share)	$ 0.49	$ 0.72	$ 0.02	$ 0.19
Stock Option
Denominator (000):
Average number of dilutive shares relating to share-based incentives	1	2	1	2
Restricted Stock
Denominator (000):
Average number of dilutive shares relating to share-based incentives	193	169	184	167