Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 3,325	$ 2,612
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on financial instruments	(5)	(138)
Other-than-temporary impairment losses recognized in income	18	21
Loss on extinguishment of debt	17	0
Loss on disposal of assets	2	3
Deferred income taxes	141	(238)
Amortization, net of accretion	752	581
Depreciation expense	92	82
Share-based compensation	135	131
Changes in operating assets and liabilities:
Receivables, net	(823)	612
Other invested assets	(17)	(26)
Other assets	(734)	(517)
Policy liabilities	(556)	275
Unearned income	(42)	970
Accounts payable and accrued expenses	756	563
Other liabilities	190	251
Income taxes	273	356
Other, net	(160)	(52)
Net cash provided by operating activities	3,364	5,486
Investing activities
Purchases of fixed maturity securities	(6,790)	(10,271)
Proceeds from fixed maturity securities:
Sales	4,971	7,668
Maturities, calls and redemptions	1,442	1,388
Payments to acquire equity securities	812	481
Proceeds from sale of equity securities	2,119	621
Purchases of other invested assets	(324)	(253)
Proceeds from sales of other invested assets	251	164
Change in collateral and settlements of non-hedging derivatives	0	65
Changes in securities lending collateral	(286)	172
Purchases of subsidiaries, net of cash acquired	(1,732)	(34)
Purchases of property and equipment	(888)	(516)
Proceeds from sales of property and equipment	0	3
Other, net	17	12
Net cash used in investing activities	(2,032)	(1,462)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings	(54)	687
Proceeds from long-term borrowings	835	0
Repayments of long-term borrowings	(1,393)	(930)
Proceeds from short-term borrowings	5,300	3,850
Repayments of short-term borrowings	(5,305)	(3,110)
Changes in securities lending payable	287	(173)
Changes in bank overdrafts	97	(127)
Proceeds from sale of put options	0	1
Proceeds from Issuance of common stock under Equity Units stock purchase contracts	1,250	0
Repurchase and retirement of common stock	(1,192)	(1,635)
Change in collateral and settlements of debt-related derivatives	22	(176)
Cash dividends	(583)	(525)
Proceeds from issuance of common stock under employee stock plans	133	178
Taxes paid through withholding of common stock under employee stock plans	(77)	(46)
Net cash used in financing activities	(680)	(2,006)
Effect of foreign exchange rates on cash and cash equivalents	(1)	4
Change in cash and cash equivalents	651	2,022
Cash and cash equivalents at beginning of period	3,609	4,075
Cash and cash equivalents at end of period	$ 4,260	$ 6,097