CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Cash Flows [Abstract]
Net income	$ 796	$ 699
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion, net	121	127
Deferred income tax expense (benefit)	6	(54)
Share-based compensation	61	68
Net realized investment losses (gains)	(40)	6
Net trading gains	(3)	(4)
Loss from equity method investments	25	20
Other-than-temporary impairments and provision for loan losses	1	0
Net losses of consolidated investment entities	2	5
Changes in operating assets and liabilities:
Restricted and segregated investments	300	175
Deferred acquisition costs	(4)	31
Other investments, net	(107)	(12)
Policyholder account balances, future policy benefits and claims, net	(384)	1,161
Derivatives, net of collateral	447	(660)
Receivables	(168)	(26)
Brokerage deposits	(135)	(69)
Accounts payable and accrued expenses	(137)	(196)
Other operating assets and liabilities of consolidated investment entities, net	1	(10)
Other, net	(46)	256
Net cash provided by operating activities	736	1,517
Available-for-Sale securities:
Proceeds from sales	276	314
Maturities, sinking fund payments and calls	2,560	2,384
Purchases	(2,495)	(3,110)
Proceeds from sales, maturities and repayments of mortgage loans	241	557
Funding of mortgage loans	(249)	(228)
Proceeds from sales and collections of other investments	142	85
Purchase of other investments	(223)	(86)
Purchase of investments by consolidated investment entities	(839)	(316)
Proceeds from sales, maturities and repayments of investments by consolidated investment entities	864	457
Purchase of land, buildings, equipment and software	(72)	(36)
Other, net	22	42
Net cash provided by investing activities	227	63
Investment certificates:
Proceeds from additions	2,507	2,168
Maturities, withdrawals and cash surrenders	(2,211)	(1,597)
Policyholder account balances:
Deposits and other additions	1,042	999
Net transfers from (to) separate accounts	(71)	83
Surrenders and other benefits	(987)	(989)
Cash paid for purchased options with deferred premiums	(132)	(163)
Cash received from purchased options with deferred premiums	39	33
Repayments of long-term debt	(5)	(251)
Dividends paid to shareholders	(244)	(239)
Repurchase of common shares	(788)	(901)
Exercise of stock options	8	4
Repayments of debt by consolidated investment entities	(24)	(60)
Net cash used in financing activities	(866)	(913)
Effect of exchange rate changes on cash	21	(38)
Net increase in cash, cash equivalents and restricted cash	118	629
Cash, cash equivalents and restricted cash, beginning balance	5,392	5,407
Net cash outflows upon the deconsolidation of VIEs	0	(346)
Cash, cash equivalents and restricted cash, ending balance	$ 5,510	$ 5,690