Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Revenues	$ 1,424.6	$ 1,446.1
Income (loss) before income taxes	58.3	59.6
Depreciation and amortization	50.1	45.5
Capital expenditures	61.5	67.5
Direct premiums and escrow fees	500.9	502.2
Agent premiums	563.8	590.4
Information and other	223.0	226.9
Net investment income (loss)	127.9	134.0
Realized (losses) gains of net investment	(3.4)	(4.5)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,424.6	1,446.1
Direct premiums and escrow fees	500.9	502.2
Agent premiums	563.8	590.4
Information and other	223.0	226.9
Net investment income (loss)	127.9	134.0
Realized (losses) gains of net investment	9.0	(7.4)
Operating Segments | Title Insurance and Services
Segment Reporting Information [Line Items]
Revenues	1,319.8	1,348.6
Income (loss) before income taxes	72.7	88.2
Depreciation and amortization	48.8	44.2
Capital expenditures	59.6	66.3
Direct premiums and escrow fees	403.2	405.6
Agent premiums	563.8	590.4
Information and other	217.2	221.5
Net investment income (loss)	116.7	124.6
Realized (losses) gains of net investment	18.9	6.5
Operating Segments | Home Warranty
Segment Reporting Information [Line Items]
Revenues	105.2	103.7
Income (loss) before income taxes	20.3	15.9
Depreciation and amortization	1.3	1.3
Capital expenditures	1.9	1.2
Direct premiums and escrow fees	97.7	96.6
Agent premiums	0.0	0.0
Information and other	5.9	5.5
Net investment income (loss)	0.9	1.4
Realized (losses) gains of net investment	0.7	0.2
Operating Segments | Corporate and Eliminations
Segment Reporting Information [Line Items]
Revenues	(0.4)	(6.2)
Income (loss) before income taxes	(34.7)	(44.5)
Depreciation and amortization	0.0	0.0
Capital expenditures	0.0	0.0
Direct premiums and escrow fees	0.0	0.0
Agent premiums	0.0	0.0
Information and other	(0.1)	(0.1)
Net investment income (loss)	10.3	8.0
Realized (losses) gains of net investment	$ (10.6)	$ (14.1)