Investments (Details - cost, unrealized gains and losses and fair value) ([TradingSecuritiesMember], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	$ 14,804,575	[1]	$ 14,354,580	[1]
Gross unrealized gains	913,765		723,788
Gross unrealized losses	78,471		149,277
Fair value	15,639,869		14,929,091
[FixedMaturitiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	13,653,615	[1]	13,394,404	[1]
Gross unrealized gains	798,405		624,614
Gross unrealized losses	56,705		77,189
Fair value	14,395,315		13,941,829
[FixedMaturitiesMember] | [USTreasuryAndGovernmentMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	1,108,513	[1]	1,084,533	[1]
Gross unrealized gains	23,173		31,283
Gross unrealized losses	762		39
Fair value	1,130,924		1,115,777
[FixedMaturitiesMember] | [USStatesAndPoliticalSubdivisionsMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	232,433	[1]	117,528	[1]
Gross unrealized gains	11,057		6,169
Gross unrealized losses	104		13
Fair value	243,386		123,684
[FixedMaturitiesMember] | [NonUsSovereignGovernmentSupranationalAndGovernmentRelatedDebtSecuritiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	2,221,272	[1]	2,807,363	[1]
Gross unrealized gains	155,144		158,900
Gross unrealized losses	743		2,172
Fair value	2,375,673		2,964,091
[FixedMaturitiesMember] | [CorporateDebtSecuritiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	6,197,594	[1]	5,461,478	[1]
Gross unrealized gains	463,221		319,090
Gross unrealized losses	4,977		33,571
Fair value	6,655,838		5,746,997
[FixedMaturitiesMember] | [AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	701,264	[1]	626,508	[1]
Gross unrealized gains	23,972		11,558
Gross unrealized losses	1,766		4,267
Fair value	723,470		633,799
[FixedMaturitiesMember] | [ResidentialMortgageBackedSecuritiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	3,128,618	[1]	3,224,850	[1]
Gross unrealized gains	118,988		94,781
Gross unrealized losses	47,682		36,730
Fair value	3,199,924		3,282,901
[FixedMaturitiesMember] | [CommercialMortgageBackedSecuritiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	63,921	[1]	72,144	[1]
Gross unrealized gains	2,850		2,833
Gross unrealized losses	671		397
Fair value	66,100		74,580
[ShortTermInvestmentsMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	150,634	[1]	42,563	[1]
Gross unrealized gains	9		22
Gross unrealized losses	91		14
Fair value	150,552		42,571
[EquitySecuritiesMember]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Cost	1,000,326	[1]	917,613	[1]
Gross unrealized gains	115,351		99,152
Gross unrealized losses	21,675		72,074
Fair value	$ 1,094,002		$ 944,691

[1] Cost is amortized cost for fixed maturities and short-term investments and cost for equity securities.