Schedule II - Condensed Financial Information, Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating expenses:
Debt extinguishment costs	$ 0	$ 321	$ 0	$ 321
Total operating expenses	2,971	2,838	8,666	7,905
Income before Income Taxes	1,033	824	3,353	2,848
Income tax expense (benefit)	259	262	854	883
Shareholders' net income	772	560	2,493	1,971
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities	0	(22)	(420)	52
Net unrealized appreciation (depreciation), derivatives	2	0	(11)	(3)
Net translation of foreign currencies	(29)	34	(136)	173
Postretirement benefits liability adjustment	13	10	31	36
Shareholders' other comprehensive income (loss)	(14)	22	(536)	258
Shareholders' comprehensive income (loss)	$ 758	$ 582	$ 1,957	$ 2,229