Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Deferred Tax Assets and Liabilities [Line Items]
Fixed maturity investments	$ 22,387	$ 35,670
Carryover of tax losses	14,177	7,429
Other assets	4,084	5,509
Total gross deferred tax assets	40,648	48,608
Unrealized gains	481,804	276,591
Employee and agent compensation	65,877	57,136
Deferred acquisition costs	791,254	712,974
Future policy benefits, unearned and advance premiums, and policy claims	311,366	355,825
Total gross deferred tax liabilities	1,650,301	1,402,526
Net deferred tax liability	$ 1,609,653	$ 1,353,918