Segment Information (Schedule of Selected Financial Information) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Revenues	$ 1,646.9	$ 2,062.5	$ 3,093.0	$ 4,096.2
Income (loss) before income taxes	178.1	141.4	237.7	271.2
Depreciation and amortization	46.1	41.6	91.6	82.6
Capital expenditures	77.2	74.7	144.7	124.3
Direct premiums and escrow fees	615.3	896.5	1,117.5	1,670.7
Agent premiums	624.7	937.2	1,215.1	1,885.0
Information and other	250.3	310.1	477.2	618.2
Net investment income (losses)	150.3	52.4	284.3	98.6
Net investment gains (losses)	(2.8)	44.3	(7.3)	43.6
Operating Segment
Segment Reporting Information [Line Items]
Revenues	1,646.9	2,062.5	3,093.0	4,096.2
Direct premiums and escrow fees	615.3	896.5	1,117.5	1,670.7
Agent premiums	624.7	937.2	1,215.1	1,885.0
Information and other	250.3	310.1	477.2	618.2
Net investment income (losses)	150.3	52.4	284.3	98.6
Net investment gains (losses)	6.3	(133.7)	(1.1)	(176.3)
Operating Segment | Title Insurance and Services
Segment Reporting Information [Line Items]
Revenues	1,530.7	2,053.8	2,879.3	4,051.1
Income (loss) before income taxes	185.7	240.7	273.9	460.2
Depreciation and amortization	44.8	40.3	89.0	80.0
Capital expenditures	74.9	73.8	141.2	122.6
Direct premiums and escrow fees	516.8	792.8	922.4	1,458.7
Agent premiums	624.7	937.2	1,215.1	1,885.0
Information and other	244.4	307.2	465.9	608.4
Net investment income (losses)	141.9	69.3	266.5	122.0
Net investment gains (losses)	2.9	(52.7)	9.4	(23.0)
Operating Segment | Home Warranty
Segment Reporting Information [Line Items]
Revenues	106.5	102.4	210.2	205.8
Income (loss) before income taxes	14.3	8.9	30.2	24.8
Depreciation and amortization	1.1	1.1	2.4	2.4
Capital expenditures	2.3	0.9	3.5	1.7
Direct premiums and escrow fees	98.5	102.1	195.1	203.2
Agent premiums	0.0	0.0	0.0	0.0
Information and other	5.9	2.7	11.4	5.5
Net investment income (losses)	1.4	1.2	2.8	2.2
Net investment gains (losses)	0.7	(3.6)	0.9	(5.1)
Operating Segment | Corporate and Eliminations
Segment Reporting Information [Line Items]
Revenues	9.7	(93.7)	3.5	(160.7)
Income (loss) before income taxes	(21.9)	(108.2)	(66.4)	(213.8)
Depreciation and amortization	0.2	0.2	0.2	0.2
Capital expenditures	0.0	0.0	0.0	0.0
Direct premiums and escrow fees	0.0	1.6	0.0	8.8
Agent premiums	0.0	0.0	0.0	0.0
Information and other	0.0	0.2	(0.1)	4.3
Net investment income (losses)	7.0	(18.1)	15.0	(25.6)
Net investment gains (losses)	$ 2.7	$ (77.4)	$ (11.4)	$ (148.2)