Schedule II-Condensed Financial Information Of Registrant (Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 7,387	$ 4,880
Fixed maturity securities, current, amortized cost	25,952	26,267
Equity securities	953	1,881
Other receivables	4,298	3,749
Other current assets	5,281	4,654
Total current assets	55,617	51,122
Other invested assets, long-term	5,685	5,225
Property and equipment, net	4,316	3,919
Other noncurrent assets	1,704	1,719
Total assets	102,772	97,460
Current liabilities:
Accounts payable and accrued expenses	5,607	4,970
Current portion of long-term debt	1,500	1,599
Other current liabilities	9,683	7,849
Total current liabilities	39,696	34,885
Long-term debt, less current portion	22,349	21,157
Other noncurrent liabilities	1,562	1,683
Total liabilities	66,378	61,332
Commitments and contingencies-Note 5
Shareholders' equity
Preferred stock, without par value, shares authorized - 100,000,000; shares issued and outstanding - none	0	0
Common stock, par value $0.01, shares authorized - 900,000,000; shares issued and outstanding - 237,958,067 and 241,770,746	2	2
Additional paid-in capital	9,084	9,148
Retained earnings	29,724	27,088
Accumulated other comprehensive loss	(2,503)	(178)	$ 150	$ (296)
Total shareholders' equity	36,307	36,060
Total liabilities and shareholders' equity	102,772	97,460
Parent Company [Member]
Current assets:
Cash and cash equivalents	942	630
Fixed maturity securities, current, amortized cost	163	515
Equity securities	104	49
Other receivables	55	40
Net due from subsidiaries	0	446
Other current assets	721	655
Total current assets	1,985	2,335
Other invested assets, long-term	783	808
Property and equipment, net	187	207
Deferred tax assets, net	313	77
Investment in subsidiaries	59,042	56,375
Other noncurrent assets	240	265
Total assets	62,550	60,067
Current liabilities:
Accounts payable and accrued expenses	894	559
Net due to subsidiaries	789	0
Current portion of long-term debt	1,500	1,599
Other current liabilities	361	344
Total current liabilities	3,544	2,502
Long-term debt, less current portion	22,324	21,132
Other noncurrent liabilities	375	373
Total liabilities	26,243	24,007
Commitments and contingencies-Note 5
Shareholders' equity
Preferred stock, without par value, shares authorized - 100,000,000; shares issued and outstanding - none	0	0
Common stock, par value $0.01, shares authorized - 900,000,000; shares issued and outstanding - 237,958,067 and 241,770,746	2	2
Additional paid-in capital	9,084	9,148
Retained earnings	29,724	27,088
Accumulated other comprehensive loss	(2,503)	(178)
Total shareholders' equity	36,307	36,060
Total liabilities and shareholders' equity	$ 62,550	$ 60,067