CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash Flows from Operating Activities:
Net income	$ 125,114us-gaap_NetIncomeLoss	$ 136,664us-gaap_NetIncomeLoss
Change in operating assets and liabilities:
Accrued investment income	(28,443)	34,480
Premiums receivable and other reinsurance balances	(19,816)	(15,627)
Deferred policy acquisition costs	2,380	64,559
Reinsurance ceded receivable balances	(64,299)	4,254
Future policy benefits, other policy claims and benefits, and other reinsurance balances	251,570	392,876
Deferred income taxes	13,144us-gaap_DeferredIncomeTaxExpenseBenefit	41,472us-gaap_DeferredIncomeTaxExpenseBenefit
Other assets and other liabilities, net	5,973	(29,340)
Amortization of net investment premiums, discounts and other	(21,666)	(25,357)
Investment related gains, net	(7,583)us-gaap_GainLossOnInvestments	(84,571)us-gaap_GainLossOnInvestments
Excess tax benefits from share-based payment arrangement	0	(668)
Other, net	59,837us-gaap_OtherNoncashIncomeExpense	22,486us-gaap_OtherNoncashIncomeExpense
Net cash provided by operating activities	316,211	541,228
Cash Flows from Investing Activities:
Sales of fixed maturity securities available-for-sale	639,676	584,491
Maturities of fixed maturity securities available-for-sale	94,994	111,854
Principal payments on mortgage loans on real estate	69,322	105,622
Principal payments on policy loans	200	485
Purchases of fixed maturity securities available-for-sale	(1,000,335)us-gaap_PaymentsToFundPolicyLoans	(917,715)us-gaap_PaymentsToFundPolicyLoans
Cash invested in mortgage loans on real estate	(272,287)	(135,802)
Cash invested in policy loans	(1)	(52,913)
Cash invested in funds withheld at interest	(32,196)	(21,466)
Payments to Acquire Property, Plant, and Equipment	(21,504)	0
Change in short-term investments	4,325	20,740
Change in other invested assets	14,092	160,427
Net cash used in investing activities	(503,714)	(144,277)
Cash Flows from Financing Activities:
Dividends to stockholders	(22,669)us-gaap_PaymentsOfDividends	(21,244)us-gaap_PaymentsOfDividends
Proceeds from (Repayments of) Secured Debt	(7,367)	0
Net change in short-term debt	0us-gaap_RepaymentsOfOtherLongTermDebt	50,000us-gaap_RepaymentsOfOtherLongTermDebt
Payments of Debt Issuance Costs	(1,184)us-gaap_PaymentsOfDebtIssuanceCosts	0us-gaap_PaymentsOfDebtIssuanceCosts
Repayments of Long-term Debt	(586)us-gaap_RepaymentsOfLongTermDebt	0us-gaap_RepaymentsOfLongTermDebt
Purchases of treasury stock	(214,665)us-gaap_PaymentsForRepurchaseOfEquity	(86,837)us-gaap_PaymentsForRepurchaseOfEquity
Excess tax benefits from share-based payment arrangement	0	668
Exercise of stock options, net	5,759	6,364
Change in cash collateral for derivative positions and other arrangements	31,109	29,680
Deposits on universal life and other investment type policies and contracts	66,329	36,257
Withdrawals on universal life and other investment type policies and contracts	(196,623)	(215,660)
Net cash (used in) provided by financing activities	(339,897)	(200,772)
Effect of exchange rate changes on cash	(35,090)	7,306
Change in cash and cash equivalents	(562,490)	203,485
Cash and cash equivalents, beginning of period	1,645,669	923,647
Cash and cash equivalents, end of period	1,083,179	1,127,132
Supplemental disclosures of cash flow information:
Net cash paid (received) for:	29,849us-gaap_InterestPaid	25,434us-gaap_InterestPaid
Income Taxes Paid, Net	(58,864)us-gaap_IncomeTaxesPaidNet	8,611us-gaap_IncomeTaxesPaidNet
Transfer to Investments	118us-gaap_TransferToInvestments	0us-gaap_TransferToInvestments
Capital Expenditures Incurred but Not yet Paid	$ 4,514	$ 0

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.

Name:	us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration