Consolidated Statement of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income	$ 2,697,000,000	$ 2,622,000,000	$ 2,523,000,000
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	(2,000,000)	(113,000,000)	(114,000,000)
Depreciation and amortization	789,000,000	763,000,000	803,000,000
Deferred federal income tax benefit	(29,000,000)	(33,000,000)	(13,000,000)
Amortization of deferred acquisition costs	4,773,000,000	4,601,000,000	4,381,000,000
Equity in income from other investments	(130,000,000)	(251,000,000)	(365,000,000)
Premiums receivable	94,000,000	(384,000,000)	(393,000,000)
Reinsurance recoverables	(162,000,000)	157,000,000	(100,000,000)
Deferred acquisition costs	(4,854,000,000)	(4,747,000,000)	(4,488,000,000)
Claims and claim adjustment expense reserves	2,622,000,000	1,047,000,000	1,246,000,000
Unearned premium reserves	592,000,000	1,008,000,000	710,000,000
Other operating activities	129,000,000	535,000,000	190,000,000
Net cash provided by operating activities	6,519,000,000	5,205,000,000	4,380,000,000
Cash flows from investing activities
Proceeds from maturities of fixed maturities	7,387,000,000	6,845,000,000	7,086,000,000
Proceeds from sales of investments:
Fixed maturities	3,057,000,000	2,187,000,000	3,546,000,000
Equity securities	111,000,000	140,000,000	178,000,000
Real estate investments	0	0	74,000,000
Other investments	281,000,000	459,000,000	511,000,000
Purchases of investments:
Fixed maturities	(14,073,000,000)	(10,711,000,000)	(13,526,000,000)
Equity securities	(112,000,000)	(94,000,000)	(117,000,000)
Real estate investments	(113,000,000)	(107,000,000)	(74,000,000)
Other investments	(487,000,000)	(497,000,000)	(537,000,000)
Net sales (purchases) of short-term securities	(566,000,000)	(957,000,000)	908,000,000
Securities transactions in the course of settlement	(47,000,000)	158,000,000	(56,000,000)
Other investing activities	(330,000,000)	(325,000,000)	(322,000,000)
Net cash used in investing activities	(4,892,000,000)	(2,902,000,000)	(2,329,000,000)
Cash flows from financing activities
Treasury stock acquired — share repurchase authorization	(625,000,000)	(1,500,000,000)	(1,270,000,000)
Treasury stock acquired — net employee share-based compensation	(47,000,000)	(48,000,000)	(51,000,000)
Dividends paid to shareholders	(861,000,000)	(844,000,000)	(814,000,000)
Payment of debt	(500,000,000)	(500,000,000)	(600,000,000)
Issuance of debt	490,000,000	492,000,000	591,000,000
Issuance of common stock -- employee share options	127,000,000	213,000,000	132,000,000
Net cash used in financing activities	(1,416,000,000)	(2,187,000,000)	(2,012,000,000)
Effect of exchange rate changes on cash	16,000,000	5,000,000	(10,000,000)
Net increase in cash	227,000,000	121,000,000	29,000,000
Cash at beginning of year	494,000,000	373,000,000	344,000,000
Cash at end of year	721,000,000	494,000,000	373,000,000
Supplemental disclosure of cash flow information
Income taxes paid	578,000,000	428,000,000	408,000,000
Interest paid	$ 339,000,000	$ 338,000,000	$ 347,000,000