Reserve for Known and Incurred but Not Reported Claims (Summary of Loss Reserves) (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Insurance [Abstract]
Known title claims, amount	$ 72,759	$ 83,805
Incurred but not reported claims	886,693	888,126
Total title claims, amount	959,452	971,931
Non-title claims, amount	54,013	53,932
Total loss reserves, amount	$ 1,013,465	$ 1,025,863	$ 983,674	$ 983,880
Known title claims, percent	7.20%	8.10%
Incurred but not reported claims, percent	87.50%	86.60%
Total title claims, percent	94.70%	94.70%
Non-title claims, percent	5.30%	5.30%
Total loss reserves, percent	100.00%	100.00%