Income Taxes - Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Fixed maturity investments	$ 4,279	$ 6,161
Carryover of tax losses	5,534	7,827
Total gross deferred tax assets	9,813	13,988
Deferred tax liabilities:
Unrealized gains	808,071	493,174
Employee and agent compensation	88,012	81,174
Deferred acquisition costs	688,034	658,457
Future policy benefits, unearned and advance premiums, and policy claims	257,640	242,124
Other liabilities	7,209	26,271
Total gross deferred tax liabilities	1,848,966	1,501,200
Net deferred tax liability	$ 1,839,153	$ 1,487,212