CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Cash Flows [Abstract]
Net income	$ 594	$ 403
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation, amortization and accretion, net	56	63
Deferred income tax expense (benefit)	104	38
Share-based compensation	32	31
Net realized investment (gains) losses	(6)	(19)
Net trading (gains) losses	(3)	(1)
Loss from equity method investments	12	12
Other than Temporary Impairments and Provision for Loan Losses		1
Net (gains) losses of consolidated investment entities	1	3
Changes in operating assets and liabilities:
Restricted and segregated investments	75	25
Deferred acquisition costs	13	5
Other investments, net	(21)	(98)
Policyholder account balances, future policy benefits and claims, net	(325)	(434)
Derivatives, net of collateral	29	304
Receivables	(78)	(59)
Brokerage deposits	(207)	77
Accounts payable and accrued expenses	(373)	(259)
Other operating assets and liabilities of consolidated investment entities, net	3
Other, net	(114)	(86)
Net cash provided by (used in) operating activities	(208)	6
Available-for-Sale securities:
Proceeds from sales	361	46
Maturities, sinking fund payments and calls	1,195	1,274
Purchases	(1,456)	(1,135)
Proceeds from sales, maturities and repayments of mortgage loans	75	117
Funding of mortgage loans	(40)	(112)
Proceeds from sales and collections of other investments	29	90
Purchase of other investments	(57)	(54)
Purchase of investments by consolidated investment entities	(116)	(285)
Proceeds from sales, maturities and repayments of investments by consolidated investment entities	130	296
Purchase of land, buildings, equipment and software	(33)	(33)
Other, net	(1)	7
Net cash provided by (used in) investing activities	87	211
Investment certificates:
Proceeds from additions	1,336	1,284
Maturities, withdrawals and cash surrenders	(1,192)	(1,083)
Policyholder account balances:
Deposits and other additions	444	502
Net transfers from (to) separate accounts	(28)	(23)
Surrenders and other benefits	(501)	(507)
Cash paid for purchased options with deferred premiums	(45)	(58)
Cash received from purchased options with deferred premiums	24
Repayments of long-term debt	(3)	(2)
Dividends paid to shareholders	(122)	(117)
Repurchase of common shares	(425)	(436)
Exercise of stock options	2	6
Repayments of debt by consolidated investment entities	(52)
Other, net	(2)
Net cash provided by (used in) financing activities	(564)	(434)
Effect of exchange rate changes on cash	12	5
Net increase (decrease) in cash, cash equivalents and restricted cash	(673)	(212)
Cash, cash equivalents and restricted cash, beginning balance	5,144	5,392
Cash, cash equivalents and restricted cash, ending balance	$ 4,471	$ 5,180