CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net income	$ 2,098	$ 1,480	$ 1,313
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion, net	198	234	248
Deferred income tax expense (benefit)	25	156	(34)
Share-based compensation	144	121	134
Net realized investment (gains) losses	(9)	(50)	(16)
Net trading (gains) losses	(12)	(7)	(6)
Loss from equity method investments	63	100	54
Other-than-temporary impairments and provision for loan losses			4
Net (gains) losses of consolidated investment entities	(47)	5	(38)
Changes in operating assets and liabilities:
Restricted and segregated investments	499	(348)	(24)
Deferred acquisition costs	4	(35)	55
Policyholder account balances, future policy benefits and claims, net	528	(441)	8
Derivatives, net of collateral	(144)	595	59
Receivables	(398)	(457)	(150)
Brokerage deposits	(255)	(198)	310
Accounts payable and accrued expenses	(100)	206	174
Other operating assets and liabilities of consolidated investment entities, net	29		(9)
Other, net	(26)	162	249
Net Cash Provided by (Used in) Operating Activities	2,597	1,523	2,331
Available-for-Sale securities:
Proceeds from sales	435	454	366
Maturities, sinking fund payments and calls	6,738	4,957	4,421
Purchases	(8,346)	(5,419)	(6,498)
Proceeds from sales, maturities and repayments of mortgage loans	295	699	810
Funding of mortgage loans	(235)	(479)	(451)
Proceeds from sales, maturities and collections of other investments	722	329	253
Purchase of other investments	(653)	(519)	(269)
Purchase of investments by consolidated investment entities	(411)	(1,268)	(845)
Proceeds from sales, maturities and repayments of investments by consolidated investment entities	1,086	1,349	1,421
Purchase of land, buildings, equipment and software	(162)	(162)	(92)
Cash paid for written options with deferred premiums	(133)	(82)	(8)
Cash received from written options with deferred premiums	133	77	78
Other, net	(56)	(107)	31
Net cash (used in) provided by investing activities	(587)	(171)	(783)
Investment certificates:
Proceeds from additions	6,238	4,725	4,250
Maturities, withdrawals and cash surrenders	(4,745)	(4,262)	(3,155)
Policyholder account balances:
Deposits and other additions	1,933	2,059	2,086
Net transfers to (from) separate accounts	(75)	(157)	127
Surrenders and other benefits	(1,904)	(1,893)	(1,932)
Cash paid for purchased options with deferred premiums	(228)	(282)	(341)
Cash received for purchased options with deferred premiums	254	116	276
Issuance of long-term debt, net of issuance costs			496
Repayments of long-term debt	(13)	(11)	(257)
Dividends paid to shareholders	(506)	(491)	(479)
Change in short-term borrowings, net			(1)
Repurchase of common shares	(1,630)	(1,485)	(1,707)
Exercise of stock options	2	15	9
Borrowings of Consolidated Investment Entities	936
Repayments of debt by consolidated investment entities	(1,528)	(118)	(517)
Other, net	3	(1)	3
Net cash provided by (used in) financing activities	(1,263)	(1,785)	(1,142)
Effect of exchange rate changes on cash	(8)	35	(75)
Net increase (decrease) in cash and cash equivalents, including amounts restricted	739	(398)	331
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, beginning balance	5,144	5,542	5,557
Net cash outflows upon the deconsolidation of VIEs			(346)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, ending balance	$ 5,883	$ 5,144	$ 5,542