Reserve for Known and Incurred but Not Reported Claims (Summary of Loss Reserves) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Insurance [Abstract]
Known title claims, amount	$ 84,569	$ 80,306
Incurred but not reported claims, amount	888,118	877,134
Total title claims, amount	972,687	957,440
Non-title claims, amount	82,037	85,239
Total loss reserves, amount	$ 1,054,724	$ 1,042,679	$ 1,026,959	$ 1,028,933
Known title claims, percent	8.00%	7.70%
Incurred but not reported claims, percent	84.20%	84.10%
Total title claims, percent	92.20%	91.80%
Non-title claims, percent	7.80%	8.20%
Total loss reserves, percent	100.00%	100.00%