Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 1,498,620	$ 1,491,157	$ 2,802,201	$ 2,788,545
Income (loss) before income taxes	229,497	201,968	371,167	295,033
Depreciation and amortization	32,884	31,058	65,818	60,805
Capital expenditures	26,166	39,931	54,142	63,532
Direct premiums and escrow fees	668,018	661,582	1,182,220	1,205,460
Agent premiums	543,847	559,004	1,045,384	1,086,718
Information and other	200,669	208,752	373,561	397,410
Net investment income	77,711	56,334	159,979	99,126
Net realized investment gains (losses)	8,375	5,485	41,057	(169)
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	1,494,842	1,489,228	2,789,205	2,788,077
Direct premiums and escrow fees	668,018	661,582	1,182,220	1,205,460
Agent premiums	543,847	559,004	1,045,384	1,086,718
Information and other	200,932	209,019	374,089	397,942
Net investment income	73,670	54,138	146,455	98,126
Net realized investment gains (losses)	8,375	5,485	41,057	(169)
Operating Segments | Title Insurance and Services
Segment Reporting Information [Line Items]
Total revenues	1,371,874	1,369,040	2,544,056	2,554,505
Income (loss) before income taxes	232,813	209,642	374,820	312,023
Depreciation and amortization	31,061	29,343	62,223	57,460
Capital expenditures	23,491	34,884	48,970	55,955
Direct premiums and escrow fees	552,358	548,616	955,114	982,768
Agent premiums	543,847	559,004	1,045,384	1,086,718
Information and other	197,779	206,095	367,870	392,116
Net investment income	70,970	51,737	141,023	93,137
Net realized investment gains (losses)	6,920	3,588	34,665	(234)
Operating Segments | Specialty Insurance
Segment Reporting Information [Line Items]
Total revenues	122,968	120,188	245,149	233,572
Income (loss) before income taxes	15,740	10,121	33,525	20,021
Depreciation and amortization	1,785	1,677	3,519	3,269
Capital expenditures	2,675	5,047	5,172	7,577
Direct premiums and escrow fees	115,660	112,966	227,106	222,692
Agent premiums	0	0	0	0
Information and other	3,153	2,924	6,219	5,826
Net investment income	2,700	2,401	5,432	4,989
Net realized investment gains (losses)	1,455	1,897	6,392	65
Corporate
Segment Reporting Information [Line Items]
Total revenues	4,127	2,208	13,686	1,027
Income (loss) before income taxes	(19,056)	(17,795)	(37,178)	(37,011)
Depreciation and amortization	38	38	76	76
Capital expenditures	0	0	0	0
Eliminations
Segment Reporting Information [Line Items]
Total revenues	(349)	(279)	(690)	(559)
Income (loss) before income taxes	0	0	0	0
Depreciation and amortization	0	0	0	0
Capital expenditures	$ 0	$ 0	$ 0	$ 0