Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 4,572	$ 4,807	$ 3,750
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses on financial instruments	(182)	(67)	206
Depreciation and amortization	1,154	1,133	1,132
Deferred income taxes	(540)	81	91
Impairment of property and equipment	198	0	0
Share-based compensation	283	294	226
Changes in operating assets and liabilities:
Receivables, net	(256)	(1,053)	(695)
Other invested assets	(32)	(48)	(1)
Other assets	(283)	(170)	(26)
Policy liabilities	3,528	1,826	(1,059)
Unearned income	202	115	(36)
Accounts payable and other liabilities	1,978	(445)	97
Income taxes	72	(325)	323
Other, net	(6)	(87)	(181)
Net cash provided by operating activities	10,688	6,061	3,827
Investing activities
Purchases of investments	(19,492)	(22,954)	(9,671)
Proceeds from sale of investments	11,318	18,598	9,662
Maturities, calls and redemptions from investments	4,741	2,437	1,938
Changes in securities lending collateral	(849)	254	(149)
Purchases of subsidiaries, net of cash acquired	(1,976)	0	(1,760)
Purchases of property and equipment	(1,021)	(1,077)	(1,208)
Other, net	(45)	(50)	(71)
Net cash used in investing activities	(7,324)	(2,792)	(1,259)
Financing activities
Net repayments of commercial paper borrowings	(150)	(297)	(107)
Proceeds from long-term borrowings	2,484	2,473	835
Repayments of long-term borrowings	(1,932)	(1,123)	(1,684)
Proceeds from short-term borrowings	970	7,590	9,120
Repayments of short-term borrowings	(1,670)	(8,035)	(9,250)
Changes in securities lending payable	849	(254)	150
Proceeds from issuance of common stock under Equity Units stock purchase agreements	0	0	1,250
Repurchase and retirement of common stock	(2,700)	(1,701)	(1,685)
Cash dividends	(954)	(818)	(776)
Proceeds from issuance of common stock under employee stock plans	176	187	173
Taxes paid through withholding of common stock under employee stock plans	(128)	(84)	(81)
Other, net	488	(204)	(186)
Net cash used in financing activities	(2,567)	(2,266)	(2,241)
Effect of foreign exchange rates on cash and cash equivalents	7	0	(2)
Change in cash and cash equivalents	804	1,003	325
Cash and cash equivalents at beginning of year	4,937	3,934	3,609
Cash and cash equivalents at end of year	$ 5,741	$ 4,937	$ 3,934