Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 1,671,196	$ 1,542,186	$ 4,473,397	$ 4,330,731
Income (loss) before income taxes	245,338	195,587	616,505	490,620
Depreciation and amortization	31,719	31,729	97,537	92,534
Capital expenditures	24,884	30,745	79,026	94,277
Direct premiums and escrow fees	728,610	649,375	1,910,830	1,854,835
Agent premiums	656,154	615,113	1,701,538	1,701,831
Information and other	208,297	198,680	581,858	596,090
Net investment income	76,628	67,874	236,607	167,000
Net realized investment gains (losses)	1,507	11,144	42,564	10,975
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	1,669,931	1,538,020	4,459,135	4,326,097
Direct premiums and escrow fees	728,610	649,375	1,910,830	1,854,835
Agent premiums	656,154	615,113	1,701,538	1,701,831
Information and other	208,552	198,944	582,640	596,886
Net investment income	75,108	63,444	221,563	161,570
Net realized investment gains (losses)	1,507	11,144	42,564	10,975
Operating Segments | Title Insurance and Services
Segment Reporting Information [Line Items]
Total revenues	1,540,741	1,413,841	4,084,795	3,968,347
Income (loss) before income taxes	253,570	206,539	628,392	518,565
Depreciation and amortization	29,822	29,978	92,043	87,438
Capital expenditures	22,869	28,342	71,839	84,296
Direct premiums and escrow fees	606,812	532,769	1,561,926	1,515,537
Agent premiums	656,154	615,113	1,701,538	1,701,831
Information and other	205,282	195,963	573,150	588,079
Net investment income	72,044	60,871	213,067	154,009
Net realized investment gains (losses)	449	9,125	35,114	8,891
Operating Segments | Specialty Insurance
Segment Reporting Information [Line Items]
Total revenues	129,190	124,179	374,340	357,750
Income (loss) before income taxes	11,021	6,201	44,546	26,220
Depreciation and amortization	1,859	1,713	5,379	4,981
Capital expenditures	2,015	2,403	7,187	9,981
Direct premiums and escrow fees	121,798	116,606	348,904	339,298
Agent premiums	0	0	0	0
Information and other	3,270	2,981	9,490	8,807
Net investment income	3,064	2,573	8,496	7,561
Net realized investment gains (losses)	1,058	2,019	7,450	2,084
Corporate
Segment Reporting Information [Line Items]
Total revenues	1,770	4,461	15,456	5,488
Income (loss) before income taxes	(19,253)	(17,153)	(56,433)	(54,165)
Depreciation and amortization	38	38	115	115
Capital expenditures	0	0	0	0
Eliminations
Segment Reporting Information [Line Items]
Total revenues	(505)	(295)	(1,194)	(854)
Income (loss) before income taxes	0	0	0	0
Depreciation and amortization	0	0	0	0
Capital expenditures	$ 0	$ 0	$ 0	$ 0