Insurance Operations - Statutory Capital and Surplus, and an Amount Representing Ten Percent of Total Liabilities for both UPCIC and APPCIC (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
UPCIC
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 401,061	$ 400,866
Ten percent of total liabilities	136,807	151,190
APPCIC
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	23,800	22,786
Ten percent of total liabilities	$ 2,190	$ 2,023