Reserve for Known and Incurred but Not Reported Claims - Reconciliation of the Net Incurred and Paid Claims Development Tables to the Liability for Claims and Claim Adjustment Expense (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Claims Development [Line Items]
Liability for unpaid claims and claim adjustment expenses - short-duration	$ 40.4
Title insurance	1,242.0	$ 1,269.3
Total loss reserves, amount	1,282.4	$ 1,325.3	$ 1,283.8	$ 1,178.0
Property and casualty insurance
Claims Development [Line Items]
Liability for unpaid claims and claim adjustment expenses - short-duration	24.7
Home warranty
Claims Development [Line Items]
Liability for unpaid claims and claim adjustment expenses - short-duration	$ 15.7