Schedule II-Condensed Financial Information Of Registrant (Statement Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 551	$ 222	$ 2,276	$ 1,523	$ 934	$ 1,183	$ 1,139	$ 1,551	$ 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
Deferred income taxes									(540)	81	91
Impairment of property and equipment									198	0	0
Depreciation and amortization									1,154	1,133	1,132
Share-based compensation									283	294	226
Changes in operating assets and liabilities:
Receivables, net									(256)	(1,053)	(695)
Other invested assets, current									(32)	(48)	(1)
Other assets									(283)	(170)	(26)
Other, net									(6)	(87)	(181)
Net cash provided by operating activities									10,688	6,061	3,827
Investing activities
Changes in securities lending collateral									(849)	254	(149)
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)
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	(234)	$ (238)	$ (242)	(240)	(202)	$ (204)	$ (206)	(206)	(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)
Cash and cash equivalents at beginning of year				4,937				3,934	4,937	3,934	3,609
Cash and cash equivalents at end of year	5,741				4,937				5,741	4,937	3,934
Parent Company [Member]
Operating activities
Net income									4,572	4,807	3,750
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiaries									(1,418)	(1,561)	(744)
Net realized (gains) losses on financial instruments									(28)	85	61
Deferred income taxes									(178)	2	(43)
Impairment of property and equipment									10	0	0
Depreciation and amortization									96	106	113
Share-based compensation									283	294	226
Changes in operating assets and liabilities:
Receivables, net									53	41	(73)
Other invested assets, current									(27)	6	(5)
Other assets									33	(235)	(225)
Amounts due to/(from) subsidiaries									1,841	(432)	2,259
Accounts payable and other liabilities									(554)	(422)	457
Income taxes									87	(282)	187
Other, net									40	2	12
Net cash provided by operating activities									4,810	2,411	5,975
Investing activities
Purchases of investments									(2,729)	(9,682)	(800)
Proceeds from sales, maturities, calls and redemptions of investments									2,593	9,457	1,865
Capitalization of subsidiaries									(2,460)	(232)	(4,379)
Changes in securities lending collateral									(234)	18	(21)
Purchases of property and equipment, net of sales									(107)	(54)	(137)
Other, net									11	0	4
Net cash used in investing activities									(2,926)	(493)	(3,468)
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)
Changes in securities lending payable									234	(18)	21
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									(1,000)	(856)	(812)
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									14	29	(83)
Net cash used in financing activities									(3,002)	(1,390)	(2,173)
Change in cash and cash equivalents									(1,118)	528	334
Cash and cash equivalents at beginning of year				$ 1,818				$ 1,290	1,818	1,290	956
Cash and cash equivalents at end of year	$ 700				$ 1,818				$ 700	$ 1,818	$ 1,290