Estimated title losses - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gain (Loss) on Securities [Line Items]
Reduction in prior policy year reserve		$ 4,000
Net increase in loss reserve estimates for prior policy years	$ 5,282	1,034	$ 6,131
Large Title Claims
Gain (Loss) on Securities [Line Items]
Total provisions related to prior policy years	$ 6,000	$ 4,400	$ 4,300