CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Statement of Cash Flows [Abstract]
Net income	$ 1,559	$ 1,303
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation, amortization and accretion, net	152	176
Deferred income tax expense (benefit)	8	(58)
Share-based compensation	105	91
Net realized investment (gains) losses	(16)	(37)
Net trading (gains) losses	(9)	(5)
Loss from equity method investments	44	41
Net (gains) losses of consolidated investment entities	(29)	3
Changes in operating assets and liabilities:
Restricted and segregated investments	349	1
Deferred acquisition costs	(61)	(31)
Other investments, net	(4)	(139)
Policyholder account balances, future policy benefits and claims, net	(523)	(353)
Derivatives, net of collateral	353	589
Receivables	(264)	(445)
Brokerage deposits	(488)	(47)
Accounts payable and accrued expenses	(98)	(19)
Other, net	31	109
Net cash provided by (used in) operating activities	1,109	1,179
Available-for-Sale securities:
Proceeds from sales	412	335
Maturities, sinking fund payments and calls	5,127	3,583
Purchases	(6,463)	(3,722)
Proceeds from sales, maturities and repayments of mortgage loans	236	348
Funding of mortgage loans	(164)	(372)
Proceeds from sales and collections of other investments	607	211
Purchase of other investments	(538)	(351)
Purchase of investments by consolidated investment entities	(327)	(1,092)
Proceeds from sales, maturities and repayments of investments by consolidated investment entities	920	1,087
Purchase of land, buildings, equipment and software	(117)	(125)
Other, net	(42)	(8)
Net cash provided by (used in) investing activities	(349)	(106)
Investment certificates:
Proceeds from additions	4,440	3,595
Maturities, withdrawals and cash surrenders	(3,497)	(3,158)
Policyholder account balances:
Deposits and other additions	1,511	1,538
Net transfers from (to) separate accounts	(89)	(120)
Surrenders and other benefits	(1,406)	(1,413)
Cash paid for purchased options with deferred premiums	(182)	(187)
Cash received from purchased options with deferred premiums	161	42
Repayments of long-term debt	(9)	(8)
Dividends paid to shareholders	(380)	(368)
Repurchase of common shares	(1,192)	(1,161)
Exercise of stock options	2	13
Borrowings of Consolidated Investment Entities	566
Repayments of debt by consolidated investment entities	(1,132)	(59)
Proceeds from (Payments for) Other Financing Activities	3
Net cash provided by (used in) financing activities	(1,204)	(1,286)
Effect of exchange rate changes on cash	(3)	32
Net increase (decrease) in cash, cash equivalents and restricted cash	(447)	(181)
Cash, cash equivalents and restricted cash, beginning balance	5,144	5,392
Cash, cash equivalents and restricted cash, ending balance	$ 4,697	$ 5,211