Insurance Operations - Statutory Capital and Surplus, and an Amount Representing Ten Percent of Total Liabilities for both UPCIC and APPCIC (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
UPCIC [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 300,597	$ 301,120
Ten percent of total liabilities	126,227	99,228
APPCIC [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	16,171	16,433
Ten percent of total liabilities	$ 820	$ 621