Estimated title losses - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Gain (Loss) on Investments [Line Items]
Ultimate loss rate for policies issued in current year	3.80%	5.10%	5.80%
Net increase in loss reserve estimates for prior years	$ 16,728,000	$ 14,275,000	$ 39,623,000
Loss reserve reductions	6,500,000
Recorded provisions	81,305,000	106,318,000	140,029,000
Change in prior years reserve, claims payment experience
Gain (Loss) on Investments [Line Items]
Net increase in loss reserve estimates for prior years	17,900,000
Recorded provisions		7,600,000	14,900,000
Change in prior years reserve, large title claims
Gain (Loss) on Investments [Line Items]
Net increase in loss reserve estimates for prior years	4,000,000
Recorded provisions	$ 3,100,000	$ 28,800,000	$ 24,300,000