Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 1,519,568	$ 1,508,344	$ 4,291,040	$ 4,071,589
Income (loss) before income taxes	17,962	166,931	285,996	396,130
Depreciation and amortization	36,000	24,491	96,292	70,905
Capital expenditures	35,765	42,792	105,856	103,815
Operating Segments | Title Insurance and Services
Segment Reporting Information [Line Items]
Revenues	1,397,262	1,395,727	3,937,119	3,750,118
Income (loss) before income taxes	181,199	188,706	476,746	448,815
Depreciation and amortization	34,363	22,994	91,471	66,510
Capital expenditures	33,750	41,948	100,059	99,887
Operating Segments | Specialty Insurance
Segment Reporting Information [Line Items]
Revenues	118,481	109,782	343,908	317,246
Income (loss) before income taxes	6,178	1,781	25,779	18,744
Depreciation and amortization	1,599	1,401	4,697	4,107
Capital expenditures	2,015	844	5,797	3,928
Corporate
Segment Reporting Information [Line Items]
Revenues	4,108	2,855	10,872	4,265
Income (loss) before income taxes	(169,415)	(23,556)	(216,529)	(71,429)
Depreciation and amortization	38	96	124	288
Capital expenditures	0	0	0	0
Eliminations
Segment Reporting Information [Line Items]
Revenues	(283)	(20)	(859)	(40)
Income (loss) before income taxes	0	0	0	0
Depreciation and amortization	0	0	0	0
Capital expenditures	$ 0	$ 0	$ 0	$ 0