Shareholders' Equity And Dividend Restrictions (Change In AOCI Includes Changes In Unrealized Gains And Losses On Investments And Pension Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017	Jan. 01, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income, Before Tax
OCI	$ (334)	$ 928	$ 537
Pension obligations OCI	(4)	14	16
Accumulated Other Comprehensive Income, Income Tax
OCI	(71)	325	188
Accumulated Other Comprehensive Income, Net of Tax
AOCI, balance at the beginning of the period	2,788
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax	2,503
AOCI, balance at the end of the period	22	2,788
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income, Before Tax
AOCI, balance at the beginning of the period	3,540	2,625	2,094
Cumulative effect of new accounting principle, before tax		(3,155)	0				$ 0
Adjusted AOCI, beginning of period		385	2,625				2,094
OCI before investment gains and losses, net, recognized in net income	(334)	1,054	653
Investment gains and losses, net, recognized in net income	(5)	(139)	(122)
OCI	(339)	915	531
AOCI, balance at the end of the period	46	3,540	2,625
Accumulated Other Comprehensive Income, Income Tax
AOCI, balance at the beginning of the period	733	908	722
Cumulative effect of new account principle, tax		(652)	0				0
Adjusted AOCI, beginning of period		81	908				722
OCI before investment gains and losses, net, recognized in net income	(71)	366	229
Investment gains and losses, net, recognized in net income	(1)	(49)	(43)
OCI	(72)	317	186
AOCI, balance at the end of the period	9	733	908
Accumulated Other Comprehensive Income, Net of Tax
AOCI, balance at the beginning of the period	2,807	1,717	1,372
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax		(2,503)	0				0
Adjusted AOCI, beginning of period		304	1,717				1,372
OCI before investment gains and losses, net, recognized in net income	(263)	688	424
Investment gains and losses, net, recognized in net income	(4)	(90)	(79)
OCI	(267)	598	345
AOCI, balance at the end of the period	37	2,807	1,717
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income, Before Tax
AOCI, balance at the beginning of the period	(12)	(26)	(42)
OCI before investment gains and losses, net, recognized in net income	(5)	12	13
Investment gains and losses, net, recognized in net income	1	2	3
OCI	(4)	14	16
AOCI, balance at the end of the period	(16)	(12)	(26)
Accumulated Other Comprehensive Income, Income Tax
AOCI, balance at the beginning of the period	(1)	(8)	(14)
OCI before investment gains and losses, net, recognized in net income	(1)	6	5
Investment gains and losses, net, recognized in net income	0	1	1
OCI	(1)	7	6
AOCI, balance at the end of the period	(2)	(1)	(8)
Accumulated Other Comprehensive Income, Net of Tax
AOCI, balance at the beginning of the period	(11)	(18)	(28)
OCI before investment gains and losses, net, recognized in net income	(4)	6	8
Investment gains and losses, net, recognized in net income	1	1	2
OCI	(3)	7	10
AOCI, balance at the end of the period	(14)	(11)	(18)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income, Before Tax
AOCI, balance at the beginning of the period	(10)	(9)	1
OCI before investment gains and losses, net, recognized in net income	(3)	8	(8)
Investment gains and losses, net, recognized in net income	12	(9)	(2)
OCI	9	(1)	(10)
AOCI, balance at the end of the period	(1)	(10)	(9)
Accumulated Other Comprehensive Income, Income Tax
AOCI, balance at the beginning of the period	(2)	(3)	1
OCI before investment gains and losses, net, recognized in net income	(1)	5	(3)
Investment gains and losses, net, recognized in net income	3	(4)	(1)
OCI	2	1	(4)
AOCI, balance at the end of the period	0	(2)	(3)
Accumulated Other Comprehensive Income, Net of Tax
AOCI, balance at the beginning of the period	(8)	(6)	0
OCI before investment gains and losses, net, recognized in net income	(2)	3	(5)
Investment gains and losses, net, recognized in net income	9	(5)	(1)
OCI	7	(2)	(6)
AOCI, balance at the end of the period	(1)	(8)	(6)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income, Before Tax
AOCI, balance at the beginning of the period	3,518	2,590	2,053
Cumulative effect of new accounting principle, before tax				$ (3,155)	$ 0	$ 0
Adjusted AOCI, beginning of period		363	2,590				2,053
Investments OCI	(339)	915	531
Pension obligations OCI	(4)	14	16
Life deferred acquisition costs, life policy reserves and other OCI	9	(1)	(10)
Total OCI	(334)	928	537
AOCI, balance at the end of the period	29	3,518	2,590
Accumulated Other Comprehensive Income, Income Tax
AOCI, balance at the beginning of the period	730	897	709
Cumulative effect of new account principle, tax				(652)	0	0
Adjusted AOCI, beginning of period		78	897				709
Investments OCI	(72)	317	186
Pension obligations OCI	(1)	7	6
Life deferred acquisition costs, life policy reserves and other OCI	2	1	(4)
Total OCI	(71)	325	188
AOCI, balance at the end of the period	7	730	897
Accumulated Other Comprehensive Income, Net of Tax
AOCI, balance at the beginning of the period	2,788	1,693	1,344
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax		(2,503)	0	$ (2,503)			0
Adjusted AOCI, beginning of period		285	1,693				$ 1,344
Investments OCI	(267)	598	345
Pension obligations OCI	(3)	7	10
Life deferred acquisition costs, life policy reserves and other OCI	7	(2)	(6)
Total OCI	(263)	603	349
Adjustment to reclassify certain tax effects from AOCI					$ 0	$ 0
AOCI, balance at the end of the period	22	2,788	1,693
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2018-02 | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income, Before Tax
Cumulative effect of new accounting principle, before tax	0	0
Accumulated Other Comprehensive Income, Income Tax
Cumulative effect of new account principle, tax	0	(492)
Accumulated Other Comprehensive Income, Net of Tax
Adjustment to reclassify certain tax effects from AOCI	0	492
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2018-02 | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income, Before Tax
Cumulative effect of new accounting principle, before tax	0	0
Accumulated Other Comprehensive Income, Income Tax
Cumulative effect of new account principle, tax	0	(492)
Accumulated Other Comprehensive Income, Net of Tax
Adjustment to reclassify certain tax effects from AOCI	$ 0	$ 492	$ 0