Condensed Financial Information of The Registrant (Details) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2006
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 3,003,000,000	$ 2,807,000,000
Debt Issuance Cost													(22,000,000)	(19,000,000)
Long-term debt													2,981,000,000	2,788,000,000
Assets
Fixed maturity securities available-for-sale													51,121,000,000	39,992,000,000
Short-term investments													64,000,000	143,000,000
Cash and cash equivalents		$ 1,449,000,000			$ 1,890,000,000	$ 1,890,000,000			$ 1,304,000,000	$ 1,890,000,000	$ 1,890,000,000	$ 1,201,000,000	1,449,000,000	1,890,000,000	$ 1,304,000,000	$ 1,201,000,000
Other assets													878,000,000	839,000,000
Total assets													76,731,000,000	64,535,000,000
Liabilities and Stockholders’ Equity
Other liabilities													1,188,000,000	1,396,000,000
Total stockholders equity													11,601,000,000	8,450,000,000	9,570,000,000	7,093,000,000
Total liabilities and stockholders’ equity													76,731,000,000	64,535,000,000
CONSOLIDATED STATEMENTS OF INCOME
Total investment related gains (losses), net										91,000,000	(170,000,000)	168,000,000
Income Tax Expense (Benefit)										262,000,000	130,000,000	(679,000,000)
Net Income (Loss) Attributable to Parent		235,000,000	$ 263,000,000	$ 202,000,000	170,000,000	110,000,000	$ 301,000,000	$ 205,000,000	100,000,000	870,000,000	716,000,000	1,822,000,000
Other Comprehensive Income (Loss), Net of Tax										2,501,000,000	(1,424,000,000)	768,000,000
Total comprehensive income (loss)										3,371,000,000	(708,000,000)	2,590,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount																	$ 850,000,000
Cash flows from operating activities
Net Income (Loss) Attributable to Parent		235,000,000	$ 263,000,000	$ 202,000,000	170,000,000	110,000,000	$ 301,000,000	$ 205,000,000	100,000,000	870,000,000	716,000,000	1,822,000,000
Other, net										(57,000,000)	(2,000,000)	24,000,000
Net cash provided by operating activities										2,307,000,000	1,581,000,000	1,982,000,000
Cash flows from investing activities
Sales of fixed maturity securities available-for-sale										13,214,000,000	9,340,000,000	7,309,000,000
Payments to Acquire Businesses, Net of Cash Acquired										4,000,000	(32,000,000)	0
Payments for (Proceeds from) Short-term Investments										199,000,000	129,000,000	52,000,000
Payments for (Proceeds from) Other Investing Activities										(304,000,000)	(365,000,000)	(122,000,000)
Net cash used in investing activities										(2,638,000,000)	(637,000,000)	(1,608,000,000)
Cash flows from financing activities
Dividends to stockholders										(163,000,000)	(140,000,000)	(117,000,000)
Purchases of treasury stock										(101,000,000)	(300,000,000)	(44,000,000)
Exercise of stock options, net										6,000,000	3,000,000	7,000,000
Maturities of Senior Debt										403,000,000	3,000,000	303,000,000
Proceeds from affiliated long-term debt issuance										(599,000,000)	0	0
Payments Of Debt Issuance Costs										(5,000,000)	0	0
Net cash used in financing activities										(121,000,000)	(322,000,000)	(324,000,000)
Change in cash and cash equivalents										(441,000,000)	586,000,000	103,000,000
Cash and cash equivalents, beginning of period					1,890,000,000				1,304,000,000	1,890,000,000	1,304,000,000	1,201,000,000
Cash and cash equivalents, end of period		1,449,000,000				1,890,000,000				1,449,000,000	1,890,000,000	1,304,000,000
Supplementary information:
Income taxes paid, net of refunds										44,000,000	142,000,000	37,000,000
Cash Acquired from Acquisition										27,000,000	5,000,000	0
Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													2,996,000,000	2,797,000,000
Debt Issuance Cost													(22,000,000)	(19,000,000)
Long-term debt	[1]												2,974,000,000	2,778,000,000
Assets
Fixed maturity securities available-for-sale													525,000,000	595,000,000
Short-term investments													19,000,000	43,000,000
Cash and cash equivalents		10,000,000			21,000,000	21,000,000			15,000,000	21,000,000	15,000,000	15,000,000	10,000,000	21,000,000	$ 15,000,000	$ 44,000,000
Investments In Subsidiary													14,486,000,000	11,033,000,000
Loans and Leases Receivable, Related Parties													1,010,000,000	1,010,000,000
Other assets													270,000,000	240,000,000
Total assets													16,320,000,000	12,942,000,000
Liabilities and Stockholders’ Equity
Long-term debt - affiliated	[2]												500,000,000	500,000,000
Other liabilities													1,244,000,000	1,213,000,000
Total stockholders equity													11,602,000,000	8,451,000,000
Total liabilities and stockholders’ equity													16,320,000,000	12,942,000,000
CONSOLIDATED STATEMENTS OF INCOME
Interest and Dividend Income, Operating	[3]									308,000,000	576,000,000	131,000,000
Total investment related gains (losses), net										4,000,000	(5,000,000)	(5,000,000)
Operating Expenses										(55,000,000)	(36,000,000)	(21,000,000)
Interest and Debt Expense										(206,000,000)	(181,000,000)	(177,000,000)
Income (loss) before income tax and undistributed earnings of subsidiaries										51,000,000	354,000,000	(72,000,000)
Income Tax Expense (Benefit)										(33,000,000)	(37,000,000)	66,000,000
Net income (loss) before undistributed earnings of subsidiaries										84,000,000	391,000,000	(138,000,000)
Equity In Undistributed Earnings Of Subsidiaries										786,000,000	325,000,000	1,960,000,000
Net Income (Loss) Attributable to Parent										870,000,000	716,000,000	1,822,000,000
Other Comprehensive Income (Loss), Net of Tax										(33,000,000)	21,000,000	(8,000,000)
Total comprehensive income (loss)										837,000,000	737,000,000	1,814,000,000
Debt Disclosure [Abstract]
Proceeds from Dividends Received										175,000,000	450,000,000
Long-term Debt													500,000,000	500,000,000
Cash flows from operating activities
Net Income (Loss) Attributable to Parent										870,000,000	716,000,000	1,822,000,000
Equity Net Earnings Subsidiaries										(786,000,000)	(325,000,000)	(1,960,000,000)
Other, net										72,000,000	37,000,000	58,000,000
Net cash provided by operating activities										156,000,000	428,000,000	(80,000,000)
Cash flows from investing activities
Sales of fixed maturity securities available-for-sale										576,000,000	482,000,000	515,000,000
Purchases of fixed maturity securities available-for-sale										(494,000,000)	(383,000,000)	(75,000,000)
Purchases Of Subsidiary Debt Securities										0	0	40,000,000
Payments for (Proceeds from) Short-term Investments										0	0	0
Payments for (Proceeds from) Other Investing Activities										0	0	125,000,000
Capital Contributions To Subsidiaries										(96,000,000)	(82,000,000)	(63,000,000)
Net cash used in investing activities										(14,000,000)	17,000,000	542,000,000
Cash flows from financing activities
Dividends to stockholders										(163,000,000)	(140,000,000)	(117,000,000)
Purchases of treasury stock										(101,000,000)	(300,000,000)	(44,000,000)
Exercise of stock options, net										6,000,000	3,000,000	7,000,000
Net Change In Cash Collateral For Loaned Securities										(92,000,000)	(2,000,000)	(37,000,000)
Maturities of Senior Debt										(397,000,000)	0	(300,000,000)
Proceeds from affiliated long-term debt issuance										(599,000,000)	0	0
Payments Of Debt Issuance Costs										(5,000,000)	0	0
Net cash used in financing activities										(153,000,000)	(439,000,000)	(491,000,000)
Change in cash and cash equivalents										(11,000,000)	6,000,000	(29,000,000)
Cash and cash equivalents, beginning of period					$ 21,000,000				$ 15,000,000	21,000,000	15,000,000	44,000,000
Cash and cash equivalents, end of period		$ 10,000,000				$ 21,000,000				10,000,000	21,000,000	15,000,000
Supplementary information:
Interest paid										192,000,000	176,000,000	186,000,000
Income taxes paid, net of refunds										$ 9,000,000	$ 93,000,000	$ 8,000,000
Senior Notes Due 2017 [Member]
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 300,000,000
Debt Instrument, Interest Rate, Stated Percentage													5.625%
Senior Notes Due 2019 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 0	400,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													6.45%
Senior Notes Due 2019 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 0	400,000,000
Senior Notes Due 2021 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													400,000,000	400,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													5.00%
Senior Notes Due 2021 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 400,000,000	399,000,000
Senior Notes Due 2023 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													399,000,000	399,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													4.70%
Senior Notes Due 2023 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 399,000,000	399,000,000
Senior Notes Due 2026 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													400,000,000	400,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													3.95%
Senior Notes Due 2026 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 400,000,000	400,000,000
Senior Notes Due 2029 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													599,000,000	0
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 600,000,000
Debt Instrument, Interest Rate, Stated Percentage													3.90%
Senior Notes Due 2029 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 599,000,000	0
Subordinated Debentures Due 2042 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													400,000,000	400,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													6.20%
Subordinated Debentures Due 2042 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 400,000,000	400,000,000
Subordinated Debentures Due 2056 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													400,000,000	400,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													5.75%
Subordinated Debentures Due 2056 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 400,000,000	400,000,000
Junior Subordinated Debentures Due 2065 [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													319,000,000	319,000,000
Debt Disclosure [Abstract]
Debt Instrument, Face Amount													$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage													4.82%
Junior Subordinated Debentures Due 2065 [Member] | Parent Company [Member]
Supplemental Condensed Financial Information Of The Registrant [Line Items]
Long-term Debt, Gross													$ 398,000,000	$ 399,000,000

[1] Long-term debt - unaffiliated consists of the following:     2019   2018 $400 million 6.45% Senior Notes due 2019   $ —
  $ 400
$400 million 5.00% Senior Notes due 2021   400
  399
$400 million 4.70% Senior Notes due 2023   399
  399
$400 million 3.95% Senior Notes due 2026   400
  400
$600 million 3.90% Senior Notes due 2029   599
  —
$400 million 6.20% Subordinated Debentures due 2042   400
  400
$400 million 5.75% Subordinated Debentures due 2056   400
  400
$400 million Variable Rate Junior Subordinated Debentures due 2065   398
  399
Subtotal   2,996
  2,797
Unamortized debt issue costs   (22 )   (19 ) Total   $ 2,974
  $ 2,778

[2] Long-term debt—affiliated in 2019 and 2018 consists of $500 million of subordinated debt issued to various operating subsidiaries.

[3] Interest/dividend income includes $175 million and $450 million of cash dividends received from consolidated subsidiaries in 2019 and 2018, respectively.