Deferred Acquisition Costs - Schedule of Analysis Deferred Acquisition Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Insurance [Abstract]
Deferred Acquisition Costs, Balance at beginning of year				$ 3,198,431				$ 2,916,732	$ 3,198,431	$ 2,916,732	$ 2,869,546
Deferred Acquisition Costs, Commissions									331,060	312,581	283,961
Deferred Acquisition Costs, Other expenses									193,203	168,237	157,864
Deferred Acquisition Costs, Total deferred costs									524,263	480,818	441,825
Deferred Acquisition Costs, Value of insurance purchased during year									8,489	175,257	0
Deferred Acquisition Costs, Foreign exchange adjustment									0	3,557	0
Deferred Acquisition Costs, Adjustment attributable to unrealized investment losses									14,906	7,234	0
Deferred Acquisition Costs, Total additions									(547,658)	(666,866)	(441,825)
Deferred Acquisition Costs, Amortized during period	(100,743)	(98,444)	(102,488)	(101,714)	(98,052)	(94,016)	(96,601)	(96,498)	(403,389)	(385,167)	(364,583)
Deferred Acquisition Costs, Foreign exchange adjustment									(5,051)	0	(1,765)
Deferred Acquisition Costs, Adjustment attributable to unrealized investment gains									0	0	(28,291)
Deferred Acquisition Costs, Total deductions									(408,440)	(385,167)	(394,639)
Deferred Acquisition Costs, Balance at end of period	$ 3,337,649				$ 3,198,431				$ 3,337,649	$ 3,198,431	$ 2,916,732