CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Statement of Cash Flows [Abstract]
Cash Acquired from Acquisition	$ 9,709
Cash Flows from Operating Activities:
Net income	273,878	408,904
Change in operating assets and liabilities:
Accrued investment income	(63,339)	(60,684)
Premiums receivable and other reinsurance balances	81,189	(102,447)
Deferred policy acquisition costs	56,286	(70,107)
Reinsurance ceded receivable balances	49,286	2,240
Future policy benefits, other policy claims and benefits, and other reinsurance balances	1,005,756	1,406,844
Deferred income taxes	276,372	(99,200)
Other assets and other liabilities, net	(293,106)	225,749
Amortization of net investment premiums, discounts and other	(70,687)	(61,644)
Investment related gains, net	(66,149)	(143,374)
Gain on repurchase of collateral finance facility securities	(46,506)	0
Excess tax benefits from share-based payment arrangement	(2,410)	262
Other, net	50,460	22,533
Net cash provided by operating activities	1,251,030	1,529,076
Cash Flows from Investing Activities:
Sales of fixed maturity securities available-for-sale	2,838,099	3,970,569
Maturities of fixed maturity securities available-for-sale	118,951	122,405
Purchases of fixed maturity securities available-for-sale	(3,496,639)	(4,660,131)
Cash invested in mortgage loans	(467,429)	(350,823)
Cash invested in policy loans	0	(8,032)
Cash invested in funds withheld at interest	(70,753)	(81,602)
Principal payments on mortgage loans on real estate	262,226	85,921
Principal payments on policy loans	33,314	24,934
Payments to Acquire Businesses, Net of Cash Acquired	(2,805)	0
Change in short-term investments	235,260	98,007
Change in other invested assets	35,341	(227,881)
Net cash used in investing activities	(514,435)	(1,026,633)
Cash Flows from Financing Activities:
Dividends to stockholders	(56,465)	(44,220)
Repurchase and repayment of collateral finance facility securities	(119,255)	0
Proceeds from Issuance of Long-term Debt	398,492	400,000
Payments of Debt Issuance Costs	(3,400)	(6,255)
Purchases of treasury stock	(269,204)	(6,924)
Excess tax benefits from share-based payment arrangement	2,410	(262)
Exercise of stock options, net	9,212	4,096
Change in cash collateral for derivatives and other arrangements	(68,635)	(62,896)
Deposits on universal life and other investment type policies and contracts	120,250	89,458
Withdrawals on universal life and other investment type policies and contracts	(550,122)	(249,190)
Net cash (used in) provided by financing activities	(536,717)	123,807
Effect of exchange rate changes on cash	(36,535)	14,610
Change in cash and cash equivalents	163,343	640,860
Cash and cash equivalents, beginning of period	1,259,892	962,870
Cash and cash equivalents, end of period	1,423,235	1,603,730
Supplementary information:
Cash paid for interest	75,003	76,514
Cash paid for income taxes, net of refunds	$ 100,429	$ 81,391