Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Statements of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities
Net income	$ 1,202	$ 690	$ 1,000
Adjustments to reconcile net income to net cash flows provided by operating activities:
Net investment income	(120)	54	(29)
Other, net	(76)	(145)	(225)
Net cash flows provided by operating activities	1,997	1,775	1,140
Cash Flows from Investing Activities
Change in short term investments	(83)	(39)	(535)
Other, net	1	16	15
Net cash flows used by investing activities	(1,228)	(705)	(225)
Cash Flows from Financing Activities
Dividends paid to common stockholders	(621)	(950)	(929)
Proceeds from the issuance of debt	0	495	496
Repayment of debt	0	(419)	(520)
Purchase of treasury stock	(18)	(18)	(23)
Other, net	(9)	(10)	(12)
Net cash flows used by financing activities	(648)	(902)	(988)
Net change in cash	117	177	(68)
Cash, beginning of year	419	242	310
Cash, end of period	536	419	242
Parent Company
Cash Flows from Operating Activities
Net income	1,202	690	1,000
Adjustments to reconcile net income to net cash flows provided by operating activities:
Equity in net income of subsidiaries	(1,304)	(812)	(1,119)
Dividends received from subsidiaries	880	975	1,065
Net investment income	0	20	21
Other, net	33	26	13
Net cash flows provided by operating activities	811	899	980
Cash Flows from Investing Activities
Change in short term investments	(163)	2	10
Capital contributions to subsidiaries	0	(1)	(2)
Other, net	0	0	0
Net cash flows used by investing activities	(163)	1	8
Cash Flows from Financing Activities
Dividends paid to common stockholders	(621)	(950)	(929)
Proceeds from the issuance of debt	0	495	496
Repayment of debt	0	(419)	(520)
Purchase of treasury stock	(18)	(18)	(23)
Other, net	(8)	(9)	(12)
Net cash flows used by financing activities	(647)	(901)	(988)
Net change in cash	1	(1)	0
Cash, beginning of year	0	1	1
Cash, end of period	$ 1	$ 0	$ 1