CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net Income	$ 684,047us-gaap_NetIncomeLoss	$ 418,837us-gaap_NetIncomeLoss	$ 631,893us-gaap_NetIncomeLoss
Change in operating assets and liabilities:
Accrued investment income	(855)	(69,875)	(12,088)
Premiums receivable and other reinsurance balances	(136,710)	(106,136)	(285,193)
Deferred policy acquisition costs	101,493	58,313	(65,050)
Reinsurance ceded receivable balances	39,345	62,058	5,293
Future policy benefits, other policy claims and benefits, and other reinsurance balances	1,625,561	1,429,697	1,792,207
Deferred income taxes	170,731us-gaap_DeferredIncomeTaxExpenseBenefit	230,778us-gaap_DeferredIncomeTaxExpenseBenefit	198,112us-gaap_DeferredIncomeTaxExpenseBenefit
Other assets and other liabilities, net	(17,244)	(186,978)	(37,831)
Amortization of net investment premiums, discounts and other	(102,459)	(95,547)	(83,787)
Investment related gains, net	(186,193)us-gaap_GainLossOnInvestments	(63,990)us-gaap_GainLossOnInvestments	(254,136)us-gaap_GainLossOnInvestments
Gain on repurchase of collateral finance notes	0	(46,506)	0
Excess tax benefits from share-based payment arrangement	3,011	(3,125)	(416)
Other, net	155,428us-gaap_OtherNoncashIncomeExpense	99,634us-gaap_OtherNoncashIncomeExpense	85,523us-gaap_OtherNoncashIncomeExpense
Net cash provided by operating activities	2,336,155	1,727,160	1,974,527
Cash flows from investing activities
Sales of fixed maturity securities available-for-sale	4,309,985	3,629,378	5,465,014
Principal payments on mortgage loans on real estate	539,789	155,237	145,423
Proceeds from Sale and Collection of Mortgage Notes Receivable	479,908	391,654	173,962
Principal payments on policy loans	63,785	33,724	40,466
Payments to Acquire Available-for-sale Securities	(6,129,956)	(4,766,275)	(6,818,378)
Purchases of fixed maturity securities available-for-sale	(721,836)	(613,413)	(491,466)
Payments to Fund Policy Loans	(103,599)us-gaap_PaymentsToFundPolicyLoans	(18)us-gaap_PaymentsToFundPolicyLoans	(58,240)us-gaap_PaymentsToFundPolicyLoans
Cash invested in funds withheld at interest	(86,588)	(90,707)	(107,289)
Purchase of business, net of cash acquired of $9,709	0	2,805	0
Payments to Acquire Property, Plant, and Equipment	(88,361)	0	0
Increase (Decrease) in Payables under Repurchase Agreements	101,203	0	0
Change in short-term investments	38,060	138,024	(101,214)
Change in other invested assets	286,665	(209,900)	(216,274)
Net cash used in investing activities	(1,310,945)	(1,335,101)	(1,967,996)
Cash flows from financing activities
Dividends to stockholders	(87,256)us-gaap_PaymentsOfDividends	(77,642)us-gaap_PaymentsOfDividends	(61,945)us-gaap_PaymentsOfDividends
Repurchase and repayment of collateral finance notes	0	(119,255)	0
Proceeds from Issuance of Secured Debt	300,000	0	0
Proceeds from long-term debt issuance	100,000	398,492	400,000
Debt issuance costs	(4,260)us-gaap_PaymentsOfDebtIssuanceCosts	(3,400)us-gaap_PaymentsOfDebtIssuanceCosts	(6,255)us-gaap_PaymentsOfDebtIssuanceCosts
Principal payments of long-term debt	(772)us-gaap_MaturitiesOfSeniorDebt	0us-gaap_MaturitiesOfSeniorDebt	0us-gaap_MaturitiesOfSeniorDebt
Purchases of treasury stock	(201,525)us-gaap_PaymentsForRepurchaseOfEquity	(269,204)us-gaap_PaymentsForRepurchaseOfEquity	(6,924)us-gaap_PaymentsForRepurchaseOfEquity
Excess tax benefits from share-based payment arrangement	(3,011)	3,125	416
Exercise of stock options, net	9,246	28,390	(3,087)
Change in cash collateral for derivative positions and other arrangements	162,435	(73,338)	(132,933)
Deposits on universal life and other investment type policies and contracts	150,922	201,957	457,711
Withdrawals on universal life and other investment type policies and contracts	(681,338)	(770,338)	(365,044)
Net cash (used in) provided by financing activities	(255,559)	(681,213)	281,939
Effect of exchange rate changes on cash	(47,629)	(47,091)	8,552
Change in cash and cash equivalents	722,022	(336,245)	297,022
Cash and cash equivalents, beginning of period	923,647	1,259,892	962,870
Cash and cash equivalents, end of period	1,645,669	923,647	1,259,892
Supplementary information:
Cash paid for interest	136,499us-gaap_InterestPaid	116,809us-gaap_InterestPaid	100,984us-gaap_InterestPaid
Cash paid for income taxes, net of refunds	70,342us-gaap_IncomeTaxesPaidNet	110,773us-gaap_IncomeTaxesPaidNet	97,000us-gaap_IncomeTaxesPaidNet
Transfer to Investments	2,001,439us-gaap_TransferToInvestments	0us-gaap_TransferToInvestments	4,861,566us-gaap_TransferToInvestments
Capital Expenditures Incurred but Not yet Paid	24,458	0	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0	(134,791)	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 0	$ 137,596	$ 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