INSURANCE LIABILITIES (Details - Undiscounted, Incurred and Paid Losses and Allocated Loss Adjustment Expenses) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($) item	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)
Claims Development [Line Items]
Change in Incurred Loss and ALAE									$ 595
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									1,429	$ 1,565	$ 5,788
Reserve strengthening charges	$ 546	$ 949	$ (26)	$ (40)	$ 212	$ 901	$ 391	$ 61
Liabilities for losses and loss adjustment expenses, net of reinsurance	51,949				51,685				51,949	51,685	61,545	$ 60,603
U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	21,159								21,159
Change in Incurred Loss and ALAE									(498)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(179)
Reserve strengthening charges									51	(31)	1,900
Incurred Impact of Adverse Development Reinsurance Agreement	(3,341)								(3,341)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,818								17,818
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	13,739								13,739
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	4,443								4,443
Unallocated Loss Adjustment Expense Prior Year Development	0				0				0	0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	11,863								11,863
U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(482)
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(2,688)				(2,032)				(2,688)	(2,032)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(6,029)								(6,029)
U.S. Excess Casualty
Claims Development [Line Items]
Change in Incurred Loss and ALAE									762
Reserve strengthening charges									1,274	254	1,100
Total	13,002								13,002
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	6,877								6,877
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	2,205								2,205
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	8,330								8,330
U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(478)
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(1,386)				(1,040)				(1,386)	(1,040)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(3,615)								(3,615)
U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	18,904								18,904
Change in Incurred Loss and ALAE									58
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(299)
Reserve strengthening charges									(127)	216	1,600
Incurred Impact of Adverse Development Reinsurance Agreement	(1,361)								(1,361)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,543								17,543
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	14,044								14,044
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	1,556								1,556
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	6,416								6,416
U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									173
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(767)				(616)				(767)	(616)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(2,128)								(2,128)
U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	18,309								18,309
Change in Incurred Loss and ALAE									355
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									278
Reserve strengthening charges									298	345	306
Incurred Impact of Adverse Development Reinsurance Agreement	(807)								(807)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,502								17,502
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	12,253								12,253
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	79								79
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	6,135								6,135
U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									49
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(13)				(42)				(13)	(42)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(820)								(820)
U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	32,175								32,175
Change in Incurred Loss and ALAE									(428)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(562)
Reserve strengthening charges									(497)	115	396
Incurred Impact of Adverse Development Reinsurance Agreement	(241)								(241)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	31,934								31,934
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	25,689								25,689
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	362								362
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	6,848								6,848
U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									37
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(73)				(79)				(73)	(79)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(314)								(314)
U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	18,311								18,311
Change in Incurred Loss and ALAE									264
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									253
Reserve strengthening charges									255	16	(32)
Incurred Impact of Adverse Development Reinsurance Agreement	(30)								(30)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	18,281								18,281
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	16,500								16,500
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(73)								(73)
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	1,738								1,738
U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									8
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(2)				(2)				(2)	(2)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(32)								(32)
Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	14,939								14,939
Change in Incurred Loss and ALAE									63
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									56
Reserve strengthening charges									58	507	320
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	8,529								8,529
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	612								612
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	7,022								7,022
Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	14,253								14,253
Change in Incurred Loss and ALAE									(24)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(23)
Reserve strengthening charges									(22)	157	11
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	(11,305)								(11,305)
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	40								40
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	2,988								2,988
Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	28,330								28,330
Change in Incurred Loss and ALAE									(116)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(125)
Reserve strengthening charges									(116)	(58)	(82)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	26,111								26,111
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	45								45
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	2,264								2,264
U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	4,517								4,517
Change in Incurred Loss and ALAE									(4)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(171)
Reserve strengthening charges									(4)	(30)	390
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	3,256								3,256
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	3,574								3,574
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	4,835								4,835
All Other
Claims Development [Line Items]
Change in Incurred Loss and ALAE									136
Prior to 2009
Claims Development [Line Items]
Reserve strengthening charges									1,163	435	2,029
Prior to 2009 | U.S. Workers Compensation
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(503)
Reserve strengthening charges									153	(7)	1,164
Prior to 2009 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(656)
Prior to 2009 | U.S. Excess Casualty
Claims Development [Line Items]
Change in Incurred Loss and ALAE									191
Reserve strengthening charges									537	164	72
Prior to 2009 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(346)
Prior to 2009 | U.S. Other Casualty
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(23)
Reserve strengthening charges									129	(8)	398
Prior to 2009 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(151)
Prior to 2009 | U.S. Financial Lines
Claims Development [Line Items]
Change in Incurred Loss and ALAE									30
Reserve strengthening charges									(1)	(34)	54
Prior to 2009 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									29
Prior to 2009 | U.S. Property and Special Risks
Claims Development [Line Items]
Change in Incurred Loss and ALAE									45
Reserve strengthening charges									39	11	6
Prior to 2009 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									6
Prior to 2009 | U.S. Personal Insurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									2
Reserve strengthening charges									2	9	(16)
Prior to 2009 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Prior to 2009 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Reserve strengthening charges									1	169	(9)
Prior to 2009 | Europe Property and Special Risks
Claims Development [Line Items]
Reserve strengthening charges									3	(6)	(1)
Prior to 2009 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Reserve strengthening charges									9	3	(4)
Prior to 2009 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Reserve strengthening charges									154	(44)	372
Prior to 2009 | All Other
Claims Development [Line Items]
Reserve strengthening charges									137	178	(7)
Total | U.S. Workers Compensation
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(5)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,818				16,825				17,818	16,825	16,000
Total | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									174
Incurred Impact of Adverse Development Reinsurance Agreement	(3,341)				(3,515)				(3,341)	(3,515)	(3,569)
Total | U.S. Excess Casualty
Claims Development [Line Items]
Change in Incurred Loss and ALAE									563
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	10,773				9,655				10,773	9,655	8,689
Total | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(132)
Incurred Impact of Adverse Development Reinsurance Agreement	(2,229)				(2,097)				(2,229)	(2,097)	(2,223)
Total | U.S. Other Casualty
Claims Development [Line Items]
Change in Incurred Loss and ALAE									25
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,543				16,705				17,543	16,705	16,056
Total | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									324
Incurred Impact of Adverse Development Reinsurance Agreement	(1,361)				(1,685)				(1,361)	(1,685)	(1,571)
Total | U.S. Financial Lines
Claims Development [Line Items]
Change in Incurred Loss and ALAE									298
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	17,502				15,567				17,502	15,567	13,747
Total | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									20
Incurred Impact of Adverse Development Reinsurance Agreement	(807)				(827)				(807)	(827)	(774)
Total | U.S. Property and Special Risks
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(531)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	31,934				28,753				31,934	28,753	23,489
Total | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									31
Incurred Impact of Adverse Development Reinsurance Agreement	(241)				(272)				(241)	(272)	(303)
Total | U.S. Personal Insurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									261
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	18,281				15,832				18,281	15,832	13,805
Total | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									8
Incurred Impact of Adverse Development Reinsurance Agreement	(30)				(38)				(30)	(38)	(30)
2009 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,697				3,714				3,697	3,714	3,708	3,606	$ 3,616	$ 3,639	$ 3,666	$ 3,608	$ 3,633	$ 3,466
Change in Incurred Loss and ALAE									(40)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(17)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 421								$ 421
Cumulative Number of Reported Claims | item	147,504								147,504
Incurred Impact of Adverse Development Reinsurance Agreement	$ (439)								$ (439)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	3,258				3,298				3,258	3,298	3,297
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	(18)								(18)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	3,058				2,968				3,058	2,968	2,887	2,780	2,621	2,390	2,120	1,756	1,328	630
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(23)
Incurred Impact of Adverse Development Reinsurance Agreement	(439)				(416)				(439)	(416)	(411)
2009 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,599				1,522				1,599	1,522	1,518	1,407	1,321	1,457	1,638	1,797	1,897	1,831
Change in Incurred Loss and ALAE									55
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									77
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 254								$ 254
Cumulative Number of Reported Claims | item	3,935								3,935
Incurred Impact of Adverse Development Reinsurance Agreement	$ (191)								$ (191)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,408				1,353				1,408	1,353	1,352
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	63								63
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,309				1,212				1,309	1,212	1,174	965	788	624	449	249	69	8
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(22)
Incurred Impact of Adverse Development Reinsurance Agreement	(191)				(169)				(191)	(169)	(166)
2009 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,884				2,855				2,884	2,855	2,863	2,880	2,818	2,697	2,582	2,586	2,517	2,416
Change in Incurred Loss and ALAE									61
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									29
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 166								$ 166
Cumulative Number of Reported Claims | item	90,390								90,390
Incurred Impact of Adverse Development Reinsurance Agreement	$ (111)								$ (111)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,773				2,712				2,773	2,712	2,714
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	55								55
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,687				2,664				2,687	2,664	2,607	2,386	2,241	2,002	1,650	1,253	842	393
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									32
Incurred Impact of Adverse Development Reinsurance Agreement	(111)				(143)				(111)	(143)	(149)
2009 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,322				2,310				2,322	2,310	2,273	2,183	2,189	2,097	1,904	1,845	1,780	1,693
Change in Incurred Loss and ALAE									6
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									12
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 62								$ 62
Cumulative Number of Reported Claims | item	22,621								22,621
Incurred Impact of Adverse Development Reinsurance Agreement	$ (32)								$ (32)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,290				2,284				2,290	2,284	2,277
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	30								30
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,129				2,092				2,129	2,092	2,056	1,964	1,838	1,614	1,273	887	499	129
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(6)
Incurred Impact of Adverse Development Reinsurance Agreement	(32)				(26)				(32)	(26)	4
2009 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,896				1,896				1,896	1,896	1,894	1,887	1,900	1,920	1,961	1,959	1,986	2,239
Change in Incurred Loss and ALAE									2
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 22								$ 22
Cumulative Number of Reported Claims | item	47,707								47,707
Incurred Impact of Adverse Development Reinsurance Agreement	$ (11)								$ (11)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,885				1,883				1,885	1,883	1,882
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	11								11
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,857				1,853				1,857	1,853	1,838	1,816	1,793	1,731	1,626	1,442	1,160	551
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									2
Incurred Impact of Adverse Development Reinsurance Agreement	(11)				(13)				(11)	(13)	(12)
2009 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,672				1,671				1,672	1,671	1,667	1,668	1,664	1,664	1,663	1,649	1,697	1,763
Change in Incurred Loss and ALAE									0
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									1
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 3								$ 3
Cumulative Number of Reported Claims | item	376,026								376,026
Incurred Impact of Adverse Development Reinsurance Agreement	$ (1)								$ (1)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,671				1,671				1,671	1,671	1,670
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	2								2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,667				1,664				1,667	1,664	1,663	1,658	1,650	1,639	1,618	1,567	1,563	1,129
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2009 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(1)
Incurred Impact of Adverse Development Reinsurance Agreement	(1)				0				(1)	0	3
2009 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,952				1,957				1,952	1,957	1,923	1,841	1,833	1,822	1,786	1,721	1,741	1,825
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(5)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 86								$ 86
Cumulative Number of Reported Claims | item	237,608								237,608
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,680				1,621				$ 1,680	1,621	1,519	1,383	1,220	1,088	924	689	430	180
2009 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	950				970				950	970	973	971	986	992	1,009	1,060	1,090	1,244
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(20)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 4								$ 4
Cumulative Number of Reported Claims | item	46,280								46,280
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 935				933				$ 935	933	931	927	910	896	854	780	624	272
2009 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,971				2,973				2,971	2,973	2,972	2,971	2,976	2,980	2,992	2,973	2,979	3,037
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(2)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 2								$ 2
Cumulative Number of Reported Claims | item	1,606,155								1,606,155
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,959				2,957				$ 2,959	2,957	2,951	2,939	2,923	2,894	2,840	2,732	2,491	1,714
2009 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	584				576				584	576	580	599	602	635	579	544	532	553
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									8
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 76								$ 76
Cumulative Number of Reported Claims | item	16,251								16,251
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 472				461				$ 472	461	447	429	409	368	286	231	134	$ 42
2010 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,278				3,267				3,278	3,267	3,286	3,214	3,211	3,148	3,125	3,049	2,706
Change in Incurred Loss and ALAE									(7)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									11
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 446								$ 446
Cumulative Number of Reported Claims | item	133,374								133,374
Incurred Impact of Adverse Development Reinsurance Agreement	$ (467)								$ (467)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,811				2,818				2,811	2,818	2,821
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	(21)								(21)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,597				2,532				2,597	2,532	2,426	2,288	2,126	1,855	1,537	1,093	550
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(18)
Incurred Impact of Adverse Development Reinsurance Agreement	(467)				(449)				(467)	(449)	(465)
2010 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,681				1,706				1,681	1,706	1,719	1,723	1,640	1,771	2,076	2,076	1,863
Change in Incurred Loss and ALAE									(20)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(25)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 331								$ 331
Cumulative Number of Reported Claims | item	3,687								3,687
Incurred Impact of Adverse Development Reinsurance Agreement	$ (255)								$ (255)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,426				1,446				1,426	1,446	1,448
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	76								76
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,265				1,217				1,265	1,217	1,052	946	795	654	475	197	10
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									5
Incurred Impact of Adverse Development Reinsurance Agreement	(255)				(260)				(255)	(260)	(271)
2010 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,504				2,494				2,504	2,494	2,503	2,384	2,341	2,192	2,243	2,109	2,132
Change in Incurred Loss and ALAE									(12)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									10
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 248								$ 248
Cumulative Number of Reported Claims | item	96,333								96,333
Incurred Impact of Adverse Development Reinsurance Agreement	$ (155)								$ (155)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,349				2,361				2,349	2,361	2,363
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	93								93
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,196				2,087				2,196	2,087	1,972	1,824	1,640	1,358	985	661	295
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(22)
Incurred Impact of Adverse Development Reinsurance Agreement	(155)				(133)				(155)	(133)	(140)
2010 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,540				1,541				1,540	1,541	1,514	1,472	1,370	1,366	1,406	1,509	1,552
Change in Incurred Loss and ALAE									(7)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(1)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 49								$ 49
Cumulative Number of Reported Claims | item	20,182								20,182
Incurred Impact of Adverse Development Reinsurance Agreement	$ (37)								$ (37)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,503				1,510				1,503	1,510	1,505
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	12								12
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,401				1,361				1,401	1,361	1,280	1,180	1,017	800	566	285	31
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(6)
Incurred Impact of Adverse Development Reinsurance Agreement	(37)				(31)				(37)	(31)	(9)
2010 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,569				2,579				2,569	2,579	2,567	2,558	2,578	2,561	2,489	2,533	2,786
Change in Incurred Loss and ALAE									(10)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(10)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 68								$ 68
Cumulative Number of Reported Claims | item	47,645								47,645
Incurred Impact of Adverse Development Reinsurance Agreement	$ (18)								$ (18)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,551				2,561				2,551	2,561	2,558
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	50								50
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,492				2,476				2,492	2,476	2,440	2,371	2,247	2,113	1,911	1,574	757
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	(18)				(18)				(18)	(18)	(9)
2010 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,815				1,817				1,815	1,817	1,817	1,819	1,820	1,819	1,819	1,809	1,843
Change in Incurred Loss and ALAE									(2)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(2)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1								$ 1
Cumulative Number of Reported Claims | item	422,639								422,639
Incurred Impact of Adverse Development Reinsurance Agreement	$ (1)								$ (1)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,814				1,816				1,814	1,816	1,816
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	0								0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,812				1,810				1,812	1,810	1,808	1,803	1,794	1,772	1,736	1,669	1,205
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2010 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	(1)				(1)				(1)	(1)	(1)
2010 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,404				1,399				1,404	1,399	1,330	1,365	1,330	1,403	1,383	1,376	1,421
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									5
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 66								$ 66
Cumulative Number of Reported Claims | item	275,528								275,528
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,148				1,124				$ 1,148	1,124	1,069	1,003	909	775	606	395	139
2010 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,282				1,281				1,282	1,281	1,280	1,283	1,304	1,327	1,388	1,544	1,679
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									1
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1								$ 1
Cumulative Number of Reported Claims | item	50,111								50,111
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,258				1,252				$ 1,258	1,252	1,245	1,236	1,207	1,168	1,077	900	413
2010 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,007				3,009				3,007	3,009	3,005	2,977	2,983	2,982	2,994	2,993	2,945
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(2)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 5								$ 5
Cumulative Number of Reported Claims | item	1,819,899								1,819,899
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,961				2,954				$ 2,961	2,954	2,943	2,924	2,889	2,833	2,723	2,480	1,690
2010 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	559				565				559	565	611	582	585	557	534	528	640
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 52								$ 52
Cumulative Number of Reported Claims | item	8,530								8,530
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 473				464				$ 473	464	455	435	404	321	243	149	$ 57
2011 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,177				3,156				3,177	3,156	3,152	3,113	3,158	3,091	2,953	2,901
Change in Incurred Loss and ALAE									5
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									21
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 490								$ 490
Cumulative Number of Reported Claims | item	124,855								124,855
Incurred Impact of Adverse Development Reinsurance Agreement	$ (495)								$ (495)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,682				2,677				2,682	2,677	2,676
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	(5)								(5)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,451				2,388				2,451	2,388	2,285	2,129	1,884	1,561	1,129	519
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(16)
Incurred Impact of Adverse Development Reinsurance Agreement	(495)				(479)				(495)	(479)	(476)
2011 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,726				1,623				1,726	1,623	1,606	1,521	1,416	1,581	1,807	1,766
Change in Incurred Loss and ALAE									69
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									103
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 370								$ 370
Cumulative Number of Reported Claims | item	3,651								3,651
Incurred Impact of Adverse Development Reinsurance Agreement	$ (290)								$ (290)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,436				1,367				1,436	1,367	1,364
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	80								80
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,214				1,069				1,214	1,069	921	716	386	225	63	5
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(34)
Incurred Impact of Adverse Development Reinsurance Agreement	(290)				(256)				(290)	(256)	(242)
2011 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,533				2,596				2,533	2,596	2,639	2,601	2,458	2,321	2,222	2,052
Change in Incurred Loss and ALAE									21
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(63)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 161								$ 161
Cumulative Number of Reported Claims | item	75,432								75,432
Incurred Impact of Adverse Development Reinsurance Agreement	$ (103)								$ (103)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,430				2,409				2,430	2,409	2,417
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	58								58
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,303				2,220				2,303	2,220	2,048	1,822	1,488	1,109	726	235
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									84
Incurred Impact of Adverse Development Reinsurance Agreement	(103)				(187)				(103)	(187)	(222)
2011 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,991				1,997				1,991	1,997	1,965	1,935	1,902	1,902	1,734	1,816
Change in Incurred Loss and ALAE									18
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 36								$ 36
Cumulative Number of Reported Claims | item	20,078								20,078
Incurred Impact of Adverse Development Reinsurance Agreement	$ (26)								$ (26)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,965				1,947				1,965	1,947	1,941
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	10								10
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,888				1,862				1,888	1,862	1,732	1,528	1,210	886	494	165
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									24
Incurred Impact of Adverse Development Reinsurance Agreement	(26)				(50)				(26)	(50)	(24)
2011 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,645				3,651				3,645	3,651	3,652	3,612	3,628	3,638	3,713	3,855
Change in Incurred Loss and ALAE									(2)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 56								$ 56
Cumulative Number of Reported Claims | item	49,597								49,597
Incurred Impact of Adverse Development Reinsurance Agreement	$ (15)								$ (15)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	3,630				3,632				3,630	3,632	3,632
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	41								41
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	3,560				3,529				3,560	3,529	3,481	3,384	3,183	2,920	2,336	1,021
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									4
Incurred Impact of Adverse Development Reinsurance Agreement	(15)				(19)				(15)	(19)	(20)
2011 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,879				1,881				1,879	1,881	1,886	1,890	1,891	1,896	1,908	1,886
Change in Incurred Loss and ALAE									(2)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(2)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1								$ 1
Cumulative Number of Reported Claims | item	412,893								412,893
Incurred Impact of Adverse Development Reinsurance Agreement	$ (1)								$ (1)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,878				1,880				1,878	1,880	1,881
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	0								0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,874				1,873				1,874	1,873	1,869	1,860	1,840	1,814	1,752	1,204
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2011 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	(1)				(1)				(1)	(1)	(5)
2011 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,557				1,540				1,557	1,540	1,494	1,493	1,409	1,375	1,307	1,361
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									17
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 71								$ 71
Cumulative Number of Reported Claims | item	265,751								265,751
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,242				1,177				$ 1,242	1,177	1,063	923	779	543	362	133
2011 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,145				1,151				1,145	1,151	1,150	1,161	1,191	1,225	1,339	1,416
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 8								$ 8
Cumulative Number of Reported Claims | item	50,560								50,560
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,101				1,094				$ 1,101	1,094	1,085	1,068	1,045	969	778	339
2011 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,261				3,261				3,261	3,261	3,262	3,258	3,269	3,267	3,301	3,241
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 5								$ 5
Cumulative Number of Reported Claims | item	1,777,851								1,777,851
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 3,228				3,219				$ 3,228	3,219	3,203	3,174	3,111	2,999	2,766	1,971
2011 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	687				700				687	700	685	676	641	576	542	534
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(13)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 83								$ 83
Cumulative Number of Reported Claims | item	7,816								7,816
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 559				549				$ 559	549	532	449	385	259	140	$ 21
2012 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,259				2,308				2,259	2,308	2,334	2,260	2,286	2,194	2,382
Change in Incurred Loss and ALAE									(21)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(49)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 418								$ 418
Cumulative Number of Reported Claims | item	70,874								70,874
Incurred Impact of Adverse Development Reinsurance Agreement	$ (466)								$ (466)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,793				1,814				1,793	1,814	1,819
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	(48)								(48)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,632				1,563				1,632	1,563	1,440	1,272	1,089	804	415
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									28
Incurred Impact of Adverse Development Reinsurance Agreement	(466)				(494)				(466)	(494)	(515)
2012 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,558				1,481				1,558	1,481	1,530	1,477	1,226	1,382	1,588
Change in Incurred Loss and ALAE									96
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									77
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 395								$ 395
Cumulative Number of Reported Claims | item	3,549								3,549
Incurred Impact of Adverse Development Reinsurance Agreement	$ (304)								$ (304)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,254				1,158				1,254	1,158	1,168
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	91								91
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,022				887				1,022	887	649	495	288	106	3
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									19
Incurred Impact of Adverse Development Reinsurance Agreement	(304)				(323)				(304)	(323)	(362)
2012 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,363				2,430				2,363	2,430	2,371	2,229	2,218	2,162	2,012
Change in Incurred Loss and ALAE									(25)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(67)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 243								$ 243
Cumulative Number of Reported Claims | item	42,226								42,226
Incurred Impact of Adverse Development Reinsurance Agreement	$ (168)								$ (168)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,195				2,220				2,195	2,220	2,208
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	75								75
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,023				1,882				2,023	1,882	1,690	1,395	1,048	743	413
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									42
Incurred Impact of Adverse Development Reinsurance Agreement	(168)				(210)				(168)	(210)	(163)
2012 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,011				1,987				2,011	1,987	1,986	1,892	1,777	1,739	1,572
Change in Incurred Loss and ALAE									17
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									24
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 150								$ 150
Cumulative Number of Reported Claims | item	20,122								20,122
Incurred Impact of Adverse Development Reinsurance Agreement	$ (90)								$ (90)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,921				1,904				1,921	1,904	1,904
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	60								60
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,689				1,625				1,689	1,625	1,497	1,252	815	406	76
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(7)
Incurred Impact of Adverse Development Reinsurance Agreement	(90)				(83)				(90)	(83)	(82)
2012 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	4,325				4,343				4,325	4,343	4,346	4,234	4,278	4,302	4,191
Change in Incurred Loss and ALAE									(12)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(18)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 95								$ 95
Cumulative Number of Reported Claims | item	48,782								48,782
Incurred Impact of Adverse Development Reinsurance Agreement	$ (19)								$ (19)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	4,306				4,318				4,306	4,318	4,319
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	76								76
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	4,170				4,137				4,170	4,137	4,001	3,785	3,420	2,716	842
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									6
Incurred Impact of Adverse Development Reinsurance Agreement	(19)				(25)				(19)	(25)	(27)
2012 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,095				2,094				2,095	2,094	2,077	2,083	2,109	2,128	2,208
Change in Incurred Loss and ALAE									2
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									1
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 2								$ 2
Cumulative Number of Reported Claims | item	403,738								403,738
Incurred Impact of Adverse Development Reinsurance Agreement	$ (2)								$ (2)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,093				2,091				2,093	2,091	2,088
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	0								0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,085				2,079				2,085	2,079	2,065	2,035	1,996	1,936	1,238
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2012 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									1
Incurred Impact of Adverse Development Reinsurance Agreement	(2)				(3)				(2)	(3)	11
2012 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,245				1,185				1,245	1,185	1,209	1,172	1,108	1,153	1,183
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									60
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 78								$ 78
Cumulative Number of Reported Claims | item	219,045								219,045
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 969				864				$ 969	864	774	642	464	320	115
2012 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,117				1,128				1,117	1,128	1,118	1,137	1,161	1,226	1,323
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(11)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 3								$ 3
Cumulative Number of Reported Claims | item	45,379								45,379
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,066				1,057				$ 1,066	1,057	1,031	985	917	725	280
2012 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,811				2,814				2,811	2,814	2,813	2,804	2,819	2,838	2,856
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(3)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 8								$ 8
Cumulative Number of Reported Claims | item	1,730,053								1,730,053
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,770				2,754				$ 2,770	2,754	2,724	2,668	2,562	2,335	1,596
2012 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	702				752				702	752	751	786	741	678	629
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(50)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 49								$ 49
Cumulative Number of Reported Claims | item	4,070								4,070
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 525				498				$ 525	498	481	414	286	194	$ 86
2013 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,974				2,032				1,974	2,032	2,060	1,950	1,880	1,932
Change in Incurred Loss and ALAE									(13)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(58)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 452								$ 452
Cumulative Number of Reported Claims | item	46,768								46,768
Incurred Impact of Adverse Development Reinsurance Agreement	$ (493)								$ (493)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,481				1,494				1,481	1,494	1,499
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	(41)								(41)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,287				1,214				1,287	1,214	1,067	879	619	282
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									45
Incurred Impact of Adverse Development Reinsurance Agreement	(493)				(538)				(493)	(538)	(561)
2013 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,226				1,178				1,226	1,178	1,258	1,113	973	1,073
Change in Incurred Loss and ALAE									56
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									48
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 397								$ 397
Cumulative Number of Reported Claims | item	2,908								2,908
Incurred Impact of Adverse Development Reinsurance Agreement	$ (301)								$ (301)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	925				869				925	869	885
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	96								96
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	661				546				661	546	382	204	104	15
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									8
Incurred Impact of Adverse Development Reinsurance Agreement	(301)				(309)				(301)	(309)	(373)
2013 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,159				2,183				2,159	2,183	2,152	1,918	1,739	1,662
Change in Incurred Loss and ALAE									(34)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(24)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 316								$ 316
Cumulative Number of Reported Claims | item	37,105								37,105
Incurred Impact of Adverse Development Reinsurance Agreement	$ (235)								$ (235)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,924				1,958				1,924	1,958	1,952
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	81								81
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,687				1,483				1,687	1,483	1,243	956	592	169
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(10)
Incurred Impact of Adverse Development Reinsurance Agreement	(235)				(225)				(235)	(225)	(200)
2013 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,488				1,541				1,488	1,541	1,597	1,643	1,691	1,767
Change in Incurred Loss and ALAE									(16)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(53)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 133								$ 133
Cumulative Number of Reported Claims | item	19,042								19,042
Incurred Impact of Adverse Development Reinsurance Agreement	$ (89)								$ (89)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,399				1,415				1,399	1,415	1,426
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	44								44
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,238				1,142				1,238	1,142	945	686	333	43
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									37
Incurred Impact of Adverse Development Reinsurance Agreement	(89)				(126)				(89)	(126)	(171)
2013 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,465				2,463				2,465	2,463	2,449	2,402	2,545	2,526
Change in Incurred Loss and ALAE									13
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									2
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 73								$ 73
Cumulative Number of Reported Claims | item	50,165								50,165
Incurred Impact of Adverse Development Reinsurance Agreement	$ (27)								$ (27)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,438				2,425				2,438	2,425	2,422
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	46								46
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,317				2,203				2,317	2,203	2,056	1,855	1,578	736
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									11
Incurred Impact of Adverse Development Reinsurance Agreement	(27)				(38)				(27)	(38)	(27)
2013 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,776				1,780				1,776	1,780	1,782	1,803	1,816	1,887
Change in Incurred Loss and ALAE									0
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(4)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 3								$ 3
Cumulative Number of Reported Claims | item	334,879								334,879
Incurred Impact of Adverse Development Reinsurance Agreement	$ (2)								$ (2)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,774				1,774				1,774	1,774	1,774
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	1								1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,766				1,759				1,766	1,759	1,744	1,705	1,634	1,109
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2013 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									4
Incurred Impact of Adverse Development Reinsurance Agreement	(2)				(6)				(2)	(6)	(8)
2013 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,223				1,237				1,223	1,237	1,182	1,211	1,241	1,190
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(14)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 116								$ 116
Cumulative Number of Reported Claims | item	186,848								186,848
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 954				823				$ 954	823	676	525	363	100
2013 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,304				1,310				1,304	1,310	1,320	1,340	1,450	1,460
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ (3)								$ (3)
Cumulative Number of Reported Claims | item	44,711								44,711
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,229				1,209				$ 1,229	1,209	1,158	1,079	839	334
2013 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,663				2,669				2,663	2,669	2,672	2,671	2,706	2,705
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(6)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 12								$ 12
Cumulative Number of Reported Claims | item	1,736,129								1,736,129
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,623				2,593				$ 2,623	2,593	2,537	2,432	2,217	1,483
2013 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	511				528				511	528	570	589	533	482
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(17)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 51								$ 51
Cumulative Number of Reported Claims | item	2,547								2,547
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 390				368				$ 390	368	321	261	154	$ 87
2014 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,794				1,862				1,794	1,862	1,866	1,764	1,729
Change in Incurred Loss and ALAE									(1)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(68)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 531								$ 531
Cumulative Number of Reported Claims | item	39,742								39,742
Incurred Impact of Adverse Development Reinsurance Agreement	$ (485)								$ (485)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,309				1,310				1,309	1,310	1,311
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	46								46
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,030				930				1,030	930	786	558	231
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									67
Incurred Impact of Adverse Development Reinsurance Agreement	(485)				(552)				(485)	(552)	(555)
2014 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,219				1,135				1,219	1,135	1,157	968	849
Change in Incurred Loss and ALAE									15
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									84
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 541								$ 541
Cumulative Number of Reported Claims | item	2,381								2,381
Incurred Impact of Adverse Development Reinsurance Agreement	$ (424)								$ (424)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	795				780				795	780	784
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	117								117
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	531				397				531	397	202	68	3
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(69)
Incurred Impact of Adverse Development Reinsurance Agreement	(424)				(355)				(424)	(355)	(373)
2014 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,920				2,017				1,920	2,017	1,973	1,729	1,756
Change in Incurred Loss and ALAE									(42)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(97)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 351								$ 351
Cumulative Number of Reported Claims | item	35,222								35,222
Incurred Impact of Adverse Development Reinsurance Agreement	$ (276)								$ (276)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,644				1,686				1,644	1,686	1,677
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	75								75
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,398				1,157				1,398	1,157	871	621	210
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									55
Incurred Impact of Adverse Development Reinsurance Agreement	(276)				(331)				(276)	(331)	(296)
2014 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,932				1,898				1,932	1,898	1,849	1,736	1,767
Change in Incurred Loss and ALAE									25
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									34
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 309								$ 309
Cumulative Number of Reported Claims | item	17,330								17,330
Incurred Impact of Adverse Development Reinsurance Agreement	$ (207)								$ (207)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,725				1,700				1,725	1,700	1,690
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	102								102
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,386				1,159				1,386	1,159	853	371	66
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(9)
Incurred Impact of Adverse Development Reinsurance Agreement	(207)				(198)				(207)	(198)	(159)
2014 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,756				2,738				2,756	2,738	2,746	2,684	2,931
Change in Incurred Loss and ALAE									15
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									18
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 140								$ 140
Cumulative Number of Reported Claims | item	60,612								60,612
Incurred Impact of Adverse Development Reinsurance Agreement	$ (64)								$ (64)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,692				2,677				2,692	2,677	2,679
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	76								76
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,434				2,296				2,434	2,296	2,083	1,748	901
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(3)
Incurred Impact of Adverse Development Reinsurance Agreement	(64)				(61)				(64)	(61)	(67)
2014 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,583				1,572				1,583	1,572	1,572	1,562	1,552
Change in Incurred Loss and ALAE									7
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									11
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 20								$ 20
Cumulative Number of Reported Claims | item	274,205								274,205
Incurred Impact of Adverse Development Reinsurance Agreement	$ (12)								$ (12)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,571				1,564				1,571	1,564	1,564
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	8								8
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,536				1,507				1,536	1,507	1,463	1,380	959
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2014 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(4)
Incurred Impact of Adverse Development Reinsurance Agreement	(12)				(8)				(12)	(8)	(8)
2014 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,242				1,289				1,242	1,289	1,279	1,247	1,262
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(47)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 252								$ 252
Cumulative Number of Reported Claims | item	177,454								177,454
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 747				620				$ 747	620	480	290	83
2014 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,564				1,553				1,564	1,553	1,566	1,578	1,564
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									11
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 27								$ 27
Cumulative Number of Reported Claims | item	53,009								53,009
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,385				1,345				$ 1,385	1,345	1,270	972	336
2014 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,643				2,651				2,643	2,651	2,660	2,677	2,668
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(8)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 19								$ 19
Cumulative Number of Reported Claims | item	1,792,742								1,792,742
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,579				2,523				$ 2,579	2,523	2,413	2,194	1,457
2014 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	383				459				383	459	453	475	379
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(76)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 76								$ 76
Cumulative Number of Reported Claims | item	2,346								2,346
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 262				233				$ 262	233	185	96	$ 21
2015 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,814				1,866				1,814	1,866	1,864	1,708
Change in Incurred Loss and ALAE									39
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(52)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 712								$ 712
Cumulative Number of Reported Claims | item	35,439								35,439
Incurred Impact of Adverse Development Reinsurance Agreement	$ (496)								$ (496)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,318				1,279				1,318	1,279	1,278
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	216								216
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	854				725				854	725	524	234
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									91
Incurred Impact of Adverse Development Reinsurance Agreement	(496)				(587)				(496)	(587)	(586)
2015 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,478				1,320				1,478	1,320	1,334	892
Change in Incurred Loss and ALAE									119
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									158
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 580								$ 580
Cumulative Number of Reported Claims | item	2,185								2,185
Incurred Impact of Adverse Development Reinsurance Agreement	$ (464)								$ (464)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,014				895				1,014	895	898
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	116								116
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	668				361				668	361	192	9
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(39)
Incurred Impact of Adverse Development Reinsurance Agreement	(464)				(425)				(464)	(425)	(436)
2015 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,749				1,847				1,749	1,847	1,778	1,340
Change in Incurred Loss and ALAE									45
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(98)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 388								$ 388
Cumulative Number of Reported Claims | item	32,422								32,422
Incurred Impact of Adverse Development Reinsurance Agreement	$ (313)								$ (313)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,436				1,391				1,436	1,391	1,377
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	75								75
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,103				783				1,103	783	321	111
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									143
Incurred Impact of Adverse Development Reinsurance Agreement	(313)				(456)				(313)	(456)	(401)
2015 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,759				1,719				1,759	1,719	1,744	1,705
Change in Incurred Loss and ALAE									27
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									40
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 433								$ 433
Cumulative Number of Reported Claims | item	15,873								15,873
Incurred Impact of Adverse Development Reinsurance Agreement	$ (326)								$ (326)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,433				1,406				1,433	1,406	1,411
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	107								107
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,051				792				1,051	792	393	66
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									(13)
Incurred Impact of Adverse Development Reinsurance Agreement	(326)				(313)				(326)	(313)	(333)
2015 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,894				2,916				2,894	2,916	2,970	3,116
Change in Incurred Loss and ALAE									(11)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(22)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 221								$ 221
Cumulative Number of Reported Claims | item	58,936								58,936
Incurred Impact of Adverse Development Reinsurance Agreement	$ (87)								$ (87)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,807				2,818				2,807	2,818	2,829
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	134								134
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,484				2,228				2,484	2,228	1,866	1,045
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									11
Incurred Impact of Adverse Development Reinsurance Agreement	(87)				(98)				(87)	(98)	(141)
2015 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,483				1,494				1,483	1,494	1,498	1,511
Change in Incurred Loss and ALAE									(3)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(11)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 13								$ 13
Cumulative Number of Reported Claims | item	259,543								259,543
Incurred Impact of Adverse Development Reinsurance Agreement	$ (11)								$ (11)
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,472				1,475				1,472	1,475	1,476
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	2								2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,439				1,411				1,439	1,411	1,320	931
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2015 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									8
Incurred Impact of Adverse Development Reinsurance Agreement	(11)				(19)				(11)	(19)	(22)
2015 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,514				1,514				1,514	1,514	1,484	1,321
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 453								$ 453
Cumulative Number of Reported Claims | item	191,382								191,382
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 671				501				$ 671	501	285	83
2015 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,676				1,698				1,676	1,698	1,685	1,729
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(22)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 40								$ 40
Cumulative Number of Reported Claims | item	58,471								58,471
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,449				1,335				$ 1,449	1,335	1,035	402
2015 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,694				2,702				2,694	2,702	2,714	2,738
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(8)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 38								$ 38
Cumulative Number of Reported Claims | item	1,771,419								1,771,419
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,574				2,456				$ 2,574	2,456	2,235	1,478
2015 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	503				550				503	550	523	439
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(47)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 85								$ 85
Cumulative Number of Reported Claims | item	2,357								2,357
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 320				238				$ 320	238	132	$ 35
2016 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,318				1,346				1,318	1,346	1,299
Change in Incurred Loss and ALAE									(28)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(28)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 625								$ 625
Cumulative Number of Reported Claims | item	29,669								29,669
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,318				1,346				1,318	1,346	1,299
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	625								625
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	521				378				521	378	147
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,055				1,029				1,055	1,029	790
Change in Incurred Loss and ALAE									26
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									26
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 703								$ 703
Cumulative Number of Reported Claims | item	1,550								1,550
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,055				1,029				1,055	1,029	790
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	703								703
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	178				66				178	66	14
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,330				1,352				1,330	1,352	1,348
Change in Incurred Loss and ALAE									(22)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(22)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 627								$ 627
Cumulative Number of Reported Claims | item	25,409								25,409
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,330				1,352				1,330	1,352	1,348
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	627								627
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	491				299				491	299	77
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,967				1,841				1,967	1,841	1,593
Change in Incurred Loss and ALAE									126
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									126
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 688								$ 688
Cumulative Number of Reported Claims | item	15,734								15,734
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,967				1,841				1,967	1,841	1,593
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	688								688
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	986				500				986	500	76
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,117				3,193				3,117	3,193	3,168
Change in Incurred Loss and ALAE									(76)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(76)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 366								$ 366
Cumulative Number of Reported Claims | item	53,727								53,727
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	3,117				3,193				3,117	3,193	3,168
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	366								366
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,367				2,039				2,367	2,039	1,018
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,533				1,533				1,533	1,533	1,536
Change in Incurred Loss and ALAE									0
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 38								$ 38
Cumulative Number of Reported Claims | item	244,935								244,935
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,533				1,533				1,533	1,533	1,536
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	38								38
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,422				1,344				1,422	1,344	857
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2016 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0	0
2016 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,754				1,686				1,754	1,686	1,538
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									68
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 565								$ 565
Cumulative Number of Reported Claims | item	227,036								227,036
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 671				427				$ 671	427	145
2016 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,738				1,698				1,738	1,698	1,644
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									40
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 58								$ 58
Cumulative Number of Reported Claims | item	59,513								59,513
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,442				1,178				$ 1,442	1,178	475
2016 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,643				2,656				2,643	2,656	2,690
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(13)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 83								$ 83
Cumulative Number of Reported Claims | item	1,791,483								1,791,483
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,416				2,199				$ 2,416	2,199	1,478
2016 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	274				285				274	285	294
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(11)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 53								$ 53
Cumulative Number of Reported Claims | item	1,646								1,646
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 163				140				$ 163	140	$ 53
2017 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	850				789				850	789
Change in Incurred Loss and ALAE									61
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									61
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 504								$ 504
Cumulative Number of Reported Claims | item	26,005								26,005
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	850				789				850	789
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	504								504
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	224				93				224	93
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	905				758				905	758
Change in Incurred Loss and ALAE									147
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									147
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 555								$ 555
Cumulative Number of Reported Claims | item	759								759
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	905				758				905	758
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	555								555
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	29				1				29	1
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	649				616				649	616
Change in Incurred Loss and ALAE									33
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									33
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 423								$ 423
Cumulative Number of Reported Claims | item	18,223								18,223
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	649				616				649	616
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	423								423
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	113				51				113	51
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,662				1,560				1,662	1,560
Change in Incurred Loss and ALAE									102
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									102
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1,017								$ 1,017
Cumulative Number of Reported Claims | item	14,702								14,702
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,662				1,560				1,662	1,560
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	1,017								1,017
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	397				66				397	66
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	4,796				5,246				4,796	5,246
Change in Incurred Loss and ALAE									(450)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(450)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 866								$ 866
Cumulative Number of Reported Claims | item	77,335								77,335
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	4,796				5,246				4,796	5,246
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	866								866
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	2,941				1,356				2,941	1,356
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,287				2,028				2,287	2,028
Change in Incurred Loss and ALAE									259
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									259
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 359								$ 359
Cumulative Number of Reported Claims | item	213,741								213,741
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,287				2,028				2,287	2,028
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	359								359
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,672				941				1,672	941
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2017 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0				0				0	0
2017 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,530				1,558				1,530	1,558
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(28)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 871								$ 871
Cumulative Number of Reported Claims | item	241,031								241,031
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 322				108				$ 322	108
2017 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,913				1,923				1,913	1,923
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(10)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 148								$ 148
Cumulative Number of Reported Claims | item	54,052								54,052
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,098				396				$ 1,098	396
2017 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,548				2,631				2,548	2,631
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									(83)
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 170								$ 170
Cumulative Number of Reported Claims | item	1,691,824								1,691,824
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,156				1,446				$ 2,156	1,446
2017 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	238				197				238	197
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement									41
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 147								$ 147
Cumulative Number of Reported Claims | item	640								640
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 59				13				$ 59	13
2018 | U.S. Workers Compensation
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	998								998
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 802								$ 802
Cumulative Number of Reported Claims | item	18,367								18,367
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	998								998
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	802								802
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	85								85
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Workers Compensation | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Excess Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	555								555
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 512								$ 512
Cumulative Number of Reported Claims | item	301								301
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	555								555
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	512								512
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Excess Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Other Casualty
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	813								813
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 703								$ 703
Cumulative Number of Reported Claims | item	11,372								11,372
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	813								813
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	703								703
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	43								43
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Other Casualty | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,637								1,637
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1,402								$ 1,402
Cumulative Number of Reported Claims | item	12,936								12,936
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	1,637								1,637
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	1,402								1,402
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	88								88
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Financial Lines | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,712								3,712
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1,609								$ 1,609
Cumulative Number of Reported Claims | item	56,580								56,580
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	3,712								3,712
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	1,609								1,609
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,067								1,067
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Property and Special Risks | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	2,188								2,188
Change in Incurred Loss and ALAE									0
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 723								$ 723
Cumulative Number of Reported Claims | item	73,321								73,321
Incurred Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0
2018 (Net of Impact of Adverse Development Reinsurance Agreement)	2,188								2,188
Total of IBNR Liabilities Net of Impact Adverse Development Reinsurance Agreement	723								723
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	1,227								1,227
Paid Impact of Adverse Development Reinsurance Agreement	0								0
2018 | U.S. Personal Insurance | Adverse Development Reinsurance
Claims Development [Line Items]
Change in Incurred Loss and ALAE									0
Incurred Impact of Adverse Development Reinsurance Agreement	0								0
2018 | Europe Casualty and Financial Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,518								1,518
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 1,118								$ 1,118
Cumulative Number of Reported Claims | item	212,169								212,169
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 125								$ 125
2018 | Europe Property and Special Risks
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	1,564								1,564
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 570								$ 570
Cumulative Number of Reported Claims | item	34,370								34,370
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 342								$ 342
2018 | Europe and Japan Personal Insurance
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	3,089								3,089
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 641								$ 641
Cumulative Number of Reported Claims | item	1,636,511								1,636,511
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,845								$ 1,845
2018 | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Incurred Losses and Allocated Loss Adjustment Expenses, Undiscounted and Net of Reinsurance	76								76
Total of IBNR Liabilities Plus Expected Development on Reported Losses	$ 35								$ 35
Cumulative Number of Reported Claims | item	282								282
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 33								$ 33
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Workers Compensation
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	153								153
Unallocated Loss Adjustment Expense Prior Year Development	77								77
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	51								51
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Excess Casualty
Claims Development [Line Items]
Total	695								695
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	537								537
Unallocated Loss Adjustment Expense Prior Year Development	42								42
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	1,274								1,274
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Other Casualty
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	129								129
Unallocated Loss Adjustment Expense Prior Year Development	43								43
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(127)								(127)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Financial Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(1)								(1)
Unallocated Loss Adjustment Expense Prior Year Development	21								21
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	298								298
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Property and Special Risks
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	39								39
Unallocated Loss Adjustment Expense Prior Year Development	26								26
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(497)								(497)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Personal Insurance
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	2								2
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	255								255
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | Europe Casualty and Financial Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	1								1
Unallocated Loss Adjustment Expense Prior Year Development	1								1
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	58								58
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | Europe Property and Special Risks
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	3								3
Unallocated Loss Adjustment Expense Prior Year Development	(2)								(2)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(22)								(22)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | Europe and Japan Personal Insurance
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	9								9
Unallocated Loss Adjustment Expense Prior Year Development	0								0
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(116)								(116)
2018 Prior Year Development Excluding the Impact of Adverse Development Reinsurance Agreement | U.S. Run-Off Long Tail Insurance Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	154								154
Unallocated Loss Adjustment Expense Prior Year Development	13								13
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(4)								(4)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Workers Compensation
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(2,688)								(2,688)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(6,029)								(6,029)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Excess Casualty
Claims Development [Line Items]
Total	(2,229)								(2,229)
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(1,386)								(1,386)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(3,615)								(3,615)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Other Casualty
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(767)								(767)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(2,128)								(2,128)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Financial Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(13)								(13)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(820)								(820)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Property and Special Risks
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(73)								(73)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(314)								(314)
Incurred Impact of Adverse Development Reinsurance Agreement | U.S. Personal Insurance
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(2)								(2)
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	(32)								(32)
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Workers Compensation
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	13,739								13,739
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	1,755				2,258				1,755	2,258
Unallocated Loss Adjustment Expense Prior Year Development	10								10
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	5,834								5,834
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Excess Casualty
Claims Development [Line Items]
Total	10,773								10,773
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	(6,877)								(6,877)
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	819				628				819	628
Unallocated Loss Adjustment Expense Prior Year Development	8								8
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	4,715								4,715
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Other Casualty
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	14,044								14,044
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	789				812				789	812
Unallocated Loss Adjustment Expense Prior Year Development	56								56
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	4,288								4,288
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Financial Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	12,253								12,253
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	66				36				66	36
Unallocated Loss Adjustment Expense Prior Year Development	27								27
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	5,315								5,315
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Property and Special Risks
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	25,689								25,689
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	289				244				289	244
Unallocated Loss Adjustment Expense Prior Year Development	58								58
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	6,534								6,534
2018 (Net of Impact of Adverse Development Reinsurance Agreement) | U.S. Personal Insurance
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	16,500								16,500
Liabilities for losses and loss adjustment expenses and prior year development before 2009, net of reinsurance	(75)				$ (77)				(75)	$ (77)
Unallocated Loss Adjustment Expense Prior Year Development	1								1
Liabilities for losses and loss adjustment expenses and prior year loss development, net of reinsurance	1,706								1,706
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Workers Compensation
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Excess Casualty
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Other Casualty
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Financial Lines
Claims Development [Line Items]
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	0								0
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Property and Special Risks
Claims Development [Line Items]
Paid Impact of Adverse Development Reinsurance Agreement	0								0
Paid Impact of Adverse Development Reinsurance Agreement | U.S. Personal Insurance
Claims Development [Line Items]
Paid Impact of Adverse Development Reinsurance Agreement	$ 0								$ 0