Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 1,612.3	$ 1,646.9	$ 3,036.9	$ 3,093.0
Income (loss) before income taxes	151.6	178.1	209.9	237.7
Depreciation and amortization	52.1	46.1	102.2	91.6
Capital expenditures	60.0	77.2	121.5	144.7
Direct premiums and escrow fees	632.7	615.3	1,133.6	1,117.5
Agent premiums	616.3	624.7	1,180.1	1,215.1
Information and other	246.6	250.3	469.6	477.2
Net investment income	129.9	150.3	257.8	284.3
Realized (losses) gains of net investment	(1.0)	(2.8)	(4.4)	(7.3)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,612.3	1,646.9	3,036.9	3,093.0
Direct premiums and escrow fees	632.7	615.3	1,133.6	1,117.5
Agent premiums	616.3	624.7	1,180.1	1,215.1
Information and other	246.6	250.3	469.6	477.2
Net investment income	129.9	150.3	257.8	284.3
Realized (losses) gains of net investment	(13.2)	6.3	(4.2)	(1.1)
Operating Segments | Title Insurance and Services
Segment Reporting Information [Line Items]
Revenues	1,521.9	1,530.7	2,841.7	2,879.3
Income (loss) before income taxes	177.4	185.7	250.1	273.9
Depreciation and amortization	50.9	44.8	99.7	89.0
Capital expenditures	58.5	74.9	118.1	141.2
Direct premiums and escrow fees	533.0	516.8	936.2	922.4
Agent premiums	616.3	624.7	1,180.1	1,215.1
Information and other	240.9	244.4	458.1	465.9
Net investment income	125.7	141.9	242.4	266.5
Realized (losses) gains of net investment	6.0	2.9	24.9	9.4
Operating Segments | Home Warranty
Segment Reporting Information [Line Items]
Revenues	106.8	106.5	212.0	210.2
Income (loss) before income taxes	16.5	14.3	36.8	30.2
Depreciation and amortization	1.1	1.1	2.4	2.4
Capital expenditures	1.5	2.3	3.4	3.5
Direct premiums and escrow fees	99.6	98.5	197.3	195.1
Agent premiums	0.0	0.0	0.0	0.0
Information and other	5.8	5.9	11.7	11.4
Net investment income	1.1	1.4	2.0	2.8
Realized (losses) gains of net investment	0.3	0.7	1.0	0.9
Operating Segments | Corporate and Eliminations
Segment Reporting Information [Line Items]
Revenues	(16.4)	9.7	(16.8)	3.5
Income (loss) before income taxes	(42.3)	(21.9)	(77.0)	(66.4)
Depreciation and amortization	0.1	0.2	0.1	0.2
Capital expenditures	0.0	0.0	0.0	0.0
Direct premiums and escrow fees	0.1	0.0	0.1	0.0
Agent premiums	0.0	0.0	0.0	0.0
Information and other	(0.1)	0.0	(0.2)	(0.1)
Net investment income	3.1	7.0	13.4	15.0
Realized (losses) gains of net investment	$ (19.5)	$ 2.7	$ (30.1)	$ (11.4)