Stockholders' Equity and Noncontrolling Interests - Statutory Capital and Surplus and Net Income of Insurance Entities in Accordance with Statutory Accounting Practices (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Life
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	$ 2,159,770	$ 1,989,586
Statutory net income	47,133	59,909	$ 46,820
Property & Casualty
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,329,782	1,183,913
Statutory net income	$ 96,269	$ 66,680	$ 72,267